WorldWideScience

Sample records for species-diverse subarctic heath

  1. Uptake of pulse injected nitrogen by soil microbes and mycorrhizal and non-mycorrhizal plants in a species-diverse subarctic heath ecosystem

    DEFF Research Database (Denmark)

    Andresen, Louise Christoffersen; Jonasson, Sven; Strom, Lena

    2008-01-01

    15N labeled ammonium, glycine or glutamic acid was injected into subarctic heath soil in situ, with the purpose of investigating how the nitrogen added in these pulses was subsequently utilized and cycled in the ecosystem. We analyzed the acquisition of 15N label in mycorrhizal and non-mycorrhiza......15N labeled ammonium, glycine or glutamic acid was injected into subarctic heath soil in situ, with the purpose of investigating how the nitrogen added in these pulses was subsequently utilized and cycled in the ecosystem. We analyzed the acquisition of 15N label in mycorrhizal and non...

  2. Nonvascular contribution to ecosystem NPP in a subarctic heath during early and late growing season

    DEFF Research Database (Denmark)

    Campioli, Matteo; Samson, Roeland; Michelsen, Anders

    2009-01-01

    significant when vascular plants are less active and ecosystems act as a source of carbon (C). To clarify these dynamics, nonvascular and vascular aboveground NPP was compared for a subarctic heath during two contrasting periods of the growing season, viz. early-mid summer and late summer-early autumn...... measurements of shoot length increase. Vascular NPP was determined by harvesting shrub and herb apical growth and considering production due to stem secondary growth of shrubs. Hylocomium splendens and Pleurozium schreberi showed highest biomass growth in late summer, whereas for D. elongatum this occurred...... weight m-2 d-1, in early and late summer, respectively, whereas in the same periods vascular NPP was 3.6 and 1.1 g dry weight m-2 d-1. The contribution of nonvascular NPP to total aboveground NPP was therefore minor in early summer but substantial in late summer, when 25% of the C accumulated...

  3. Molecular analyses reveal high species diversity of trematodes in a sub-Arctic lake

    Science.gov (United States)

    Soldánová, Miroslava; Georgieva, Simona; Roháčováa, Jana; Knudsen, Rune; Kuhn, Jesper A.; Henriksen, Eirik H.; Siwertsson, Anna; Shaw, Jenny C.; Kuris, Armand M.; Amundsen, Per-Arne; Scholz, Tomáš; Lafferty, Kevin D.; Kostadinova, Aneta

    2017-01-01

    To identify trematode diversity and life-cycles in the sub-Arctic Lake Takvatn, Norway, we characterised 120 trematode isolates from mollusc first intermediate hosts, metacercariae from second intermediate host fishes and invertebrates, and adults from fish and invertebrate definitive hosts, using molecular techniques. Phylogenies based on nuclear and/or mtDNA revealed high species richness (24 species or species-level genetic lineages), and uncovered trematode diversity (16 putative new species) from five families typical in lake ecosystems (Allocreadiidae, Diplostomidae, Plagiorchiidae, Schistosomatidae and Strigeidae). Sampling potential invertebrate hosts allowed matching of sequence data for different stages, thus achieving molecular elucidation of trematode life-cycles and exploration of host-parasite interactions. Phylogenetic analyses also helped identify three major mollusc intermediate hosts (Radix balthica, Pisidium casertanum and Sphaerium sp.) in the lake. Our findings increase the known trematode diversity at the sub-Arctic Lake Takvatn, showing that digenean diversity is high in this otherwise depauperate sub-Arctic freshwater ecosystem, and indicating that sub-Arctic and Arctic ecosystems may be characterised by unique trematode assemblages.

  4. Molecular analyses reveal high species diversity of trematodes in a sub-Arctic lake

    Czech Academy of Sciences Publication Activity Database

    Soldánová, Miroslava; Georgieva, Simona; Roháčová, Jana; Knudsen, R.; Kuhn, J. A.; Henriksen, E. H.; Siwertsson, A.; Shaw, J. C.; Kuris, A. M.; Amundsen, P.-A.; Scholz, Tomáš; Lafferty, K. D.; Kostadinova, Aneta

    2017-01-01

    Roč. 47, č. 6 (2017), s. 327-345 ISSN 0020-7519 R&D Projects: GA ČR GA15-14198S; GA ČR GAP505/10/1562 Institutional support: RVO:60077344 Keywords : Trematode diversity * intermediate hosts * phylogeny * mitochondrial DNA * nuclear DNA * Lake Takvatn * Norway * Sub-Arctic Subject RIV: EG - Zoology OBOR OECD: Zoology Impact factor: 3.730, year: 2016

  5. Impact of decade-long warming, nutrient addition and shading on emission and carbon isotopic composition of CO2 from two subarctic dwarf shrub heaths

    DEFF Research Database (Denmark)

    Ravn, Nynne R.; Ambus, Per Lennart; Michelsen, Anders

    2017-01-01

    This study investigated ecosystem respiration, soil respiration and carbon isotopic composition in CO2 emitted from two subarctic shrub heaths with contrasting moisture regimes. The reported measurements were conducted 22 years (mesic heath) and 12 years (wet heath) upon initiation of in situ...... the growing season. However, there was a tendency across growing season towards an increased δ13C source value after 22 years of warming in the mesic shrub heath, and the effect was statistically significant in June, indicating increased decomposition of 13C enriched material. Hence, although more of the old...

  6. Nitrogen Uptake During Fall, Winter and Spring Differs Among Plant Functional Groups in a Subarctic Heath Ecosystem

    DEFF Research Database (Denmark)

    Larsen, Klaus Steenberg; Michelsen, Anders; Jonasson, Sven

    2012-01-01

    Nitrogen (N) is a critical resource for plant growth in tundra ecosystems, and species differences in the timing of N uptake may be an important feature regulating community composition and ecosystem productivity. We added 15N-labelled glycine to a subarctic heath tundra dominated by dwarf shrubs...... to 37 ± 7% by April indicating significant microbial N turnover prior to spring thaw. Only the evergreen dwarf shrubs showed active 15N acquisition before early May indicating that they had the highest potential of all functional groups for acquiring nutrients that became available in early spring....... The faster-growing deciduous shrubs did not resume 15N acquisition until after early May indicating that they relied more on nitrogen made available later during the spring/early summer. The graminoids and mosses had no significant increases in 15N tracer recovery or tissue 15N tracer concentrations after...

  7. Moisture effects on temperature sensitivity of CO2 exchange in a subarctic heath ecosystem

    DEFF Research Database (Denmark)

    Illeris, Lotte; Christensen, TR; Mastepanov, M

    2004-01-01

    Carbon fluxes between natural ecosystems and the atmosphere have received increased attention in recent years due to the impact they have on climate. In order to investigate independently how soil moisture and temperature control carbon fluxes into and out of a dry subarctic dwarf shrub dominated...

  8. Impacts of Climate Change Induced Vegetation Responses on BVOC Emissions from Subarctic Heath Ecosystems

    DEFF Research Database (Denmark)

    Valolahti, Hanna Maritta

    The role of biogenic volatile organic compounds (BVOCs) affecting Earths’ climate system is one of the greatest uncertainties when modelling the global climate change. BVOCs presence in the atmosphere can have both positive and negative climate feedback mechanisms when they involve atmospheric...... chemistry and physics. Vegetation is the main source of BVOCs. Their production is directly linked to temperature and the foliar biomass. On global scale, vegetation in subarctic and arctic regions has been modeled to have only minor contribution to annual total BVOC emissions. In these regions cold...... temperature has been regulating annual plant biomass production, but ongoing global warming is more pronounced in these regions than what the global average is. This may increase the importance of subarctic and arctic vegetation as a source of BVOC emissions in near future. This thesis aims to increase...

  9. Seasonal variations in methane fluxes in response to summer warming and leaf litter addition in a subarctic heath ecosystem

    Science.gov (United States)

    Pedersen, Emily Pickering; Elberling, Bo; Michelsen, Anders

    2017-08-01

    Methane (CH4) is a powerful greenhouse gas controlled by both biotic and abiotic processes. Few studies have investigated CH4 fluxes in subarctic heath ecosystems, and climate change-induced shifts in CH4 flux and the overall carbon budget are therefore largely unknown. Hence, there is an urgent need for long-term in situ experiments allowing for the study of ecosystem processes over time scales relevant to environmental change. Here we present in situ CH4 and CO2 flux measurements from a wet heath ecosystem in northern Sweden subjected to 16 years of manipulations, including summer warming with open-top chambers, birch leaf litter addition, and the combination thereof. Throughout the snow-free season, the ecosystem was a net sink of CH4 and CO2 (CH4 -0.27 mg C m-2 d-1; net ecosystem exchange -1827 mg C m-2 d-1), with highest CH4 uptake rates (-0.70 mg C m-2 d-1) during fall. Warming enhanced net CO2 flux, while net CH4 flux was governed by soil moisture. Litter addition and the combination with warming significantly increased CH4 uptake rates, explained by a pronounced soil drying effect of up to 32% relative to ambient conditions. Both warming and litter addition also increased the seasonal average concentration of dissolved organic carbon in the soil. The site was a carbon sink with a net uptake of 60 g C m-2 over the snow-free season. However, warming reduced net carbon uptake by 77%, suggesting that this ecosystem type might shift from snow-free season sink to source with increasing summer temperatures.

  10. Impacts of extreme winter warming events on plant physiology in a sub-Arctic heath community.

    Science.gov (United States)

    Bokhorst, Stef; Bjerke, Jarle W; Davey, Matthew P; Taulavuori, Kari; Taulavuori, Erja; Laine, Kari; Callaghan, Terry V; Phoenix, Gareth K

    2010-10-01

    Insulation provided by snow cover and tolerance of freezing by physiological acclimation allows Arctic plants to survive cold winter temperatures. However, both the protection mechanisms may be lost with winter climate change, especially during extreme winter warming events where loss of snow cover from snow melt results in exposure of plants to warm temperatures and then returning extreme cold in the absence of insulating snow. These events cause considerable damage to Arctic plants, but physiological responses behind such damage remain unknown. Here, we report simulations of extreme winter warming events using infrared heating lamps and soil warming cables in a sub-Arctic heathland. During these events, we measured maximum quantum yield of photosystem II (PSII), photosynthesis, respiration, bud swelling and associated bud carbohydrate changes and lipid peroxidation to identify physiological responses during and after the winter warming events in three dwarf shrub species: Empetrum hermaphroditum, Vaccinium vitis-idaea and Vaccinium myrtillus. Winter warming increased maximum quantum yield of PSII, and photosynthesis was initiated for E. hermaphroditum and V. vitis-idaea. Bud swelling, bud carbohydrate decreases and lipid peroxidation were largest for E. hermaphroditum, whereas V. myrtillus and V. vitis-idaea showed no or less strong responses. Increased physiological activity and bud swelling suggest that sub-Arctic plants can initiate spring-like development in response to a short winter warming event. Lipid peroxidation suggests that plants experience increased winter stress. The observed differences between species in physiological responses are broadly consistent with interspecific differences in damage seen in previous studies, with E. hermaphroditum and V. myrtillus tending to be most sensitive. This suggests that initiation of spring-like development may be a major driver in the damage caused by winter warming events that are predicted to become more

  11. Significance of cold-season respiration and photosynthesis in a subarctic heath ecosystem in Northern Sweden

    DEFF Research Database (Denmark)

    Larsen, Klaus Steenberg; Ibrom, Andreas; Jonasson, S.

    2007-01-01

    While substantial cold-season respiration has been documented in most arctic and alpine ecosystems in recent years, the significance of cold-season photosynthesis in these biomes is still believed to be small. In a mesic, subartic heath during both the cold and warm season, we measured in situ...... ecosystem respiration and photosynthesis with a chamber technique at ambient conditions and at artificially, increased frequency of freeze-thaw (FT) cycles during fall and spring. We fitted the measured ecosystem exchange rates to respiration and photosynthesis models with R-2-values ranging from 0.81 to 0.......85. As expected, estimated cold-season (October, November, April and May) respiration was significant and accounted for at least 22% of the annual respiratory CO2 flux. More surprisingly, estimated photosynthesis during this period accounted for up to 19% of the annual gross CO2 uptake, suggesting that cold...

  12. Challenges in modelling isoprene and monoterpene emission dynamics of Arctic plants: a case study from a subarctic tundra heath

    Science.gov (United States)

    Tang, Jing; Schurgers, Guy; Valolahti, Hanna; Faubert, Patrick; Tiiva, Päivi; Michelsen, Anders; Rinnan, Riikka

    2016-12-01

    The Arctic is warming at twice the global average speed, and the warming-induced increases in biogenic volatile organic compounds (BVOCs) emissions from Arctic plants are expected to be drastic. The current global models' estimations of minimal BVOC emissions from the Arctic are based on very few observations and have been challenged increasingly by field data. This study applied a dynamic ecosystem model, LPJ-GUESS, as a platform to investigate short-term and long-term BVOC emission responses to Arctic climate warming. Field observations in a subarctic tundra heath with long-term (13-year) warming treatments were extensively used for parameterizing and evaluating BVOC-related processes (photosynthesis, emission responses to temperature and vegetation composition). We propose an adjusted temperature (T) response curve for Arctic plants with much stronger T sensitivity than the commonly used algorithms for large-scale modelling. The simulated emission responses to 2 °C warming between the adjusted and original T response curves were evaluated against the observed warming responses (WRs) at short-term scales. Moreover, the model responses to warming by 4 and 8 °C were also investigated as a sensitivity test. The model showed reasonable agreement to the observed vegetation CO2 fluxes in the main growing season as well as day-to-day variability of isoprene and monoterpene emissions. The observed relatively high WRs were better captured by the adjusted T response curve than by the common one. During 1999-2012, the modelled annual mean isoprene and monoterpene emissions were 20 and 8 mg C m-2 yr-1, with an increase by 55 and 57 % for 2 °C summertime warming, respectively. Warming by 4 and 8 °C for the same period further elevated isoprene emission for all years, but the impacts on monoterpene emissions levelled off during the last few years. At hour-day scale, the WRs seem to be strongly impacted by canopy air T, while at the day-year scale, the WRs are a combined

  13. Twenty-Two Years of Warming, Fertilisation and Shading of Subarctic Heath Shrubs Promote Secondary Growth and Plasticity but Not Primary Growth

    Science.gov (United States)

    Campioli, Matteo; Leblans, Niki; Michelsen, Anders

    2012-01-01

    Most manipulation experiments simulating global change in tundra were short-term or did not measure plant growth directly. Here, we assessed the growth of three shrubs (Cassiope tetragona, Empetrum hermaphroditum and Betula nana) at a subarctic heath in Abisko (Northern Sweden) after 22 years of warming (passive greenhouses), fertilisation (nutrients addition) and shading (hessian fabric), and compare this to observations from the first decade of treatment. We assessed the growth rate of current-year leaves and apical stem (primary growth) and cambial growth (secondary growth), and integrated growth rates with morphological measurements and species coverage. Primary- and total growth of Cassiope and Empetrum were unaffected by manipulations, whereas growth was substantially reduced under fertilisation and shading (but not warming) for Betula. Overall, shrub height and length tended to increase under fertilisation and warming, whereas branching increased mostly in shaded Cassiope. Morphological changes were coupled to increased secondary growth under fertilisation. The species coverage showed a remarkable increase in graminoids in fertilised plots. Shrub response to fertilisation was positive in the short-term but changed over time, likely because of an increased competition with graminoids. More erected postures and large, canopies (requiring enhanced secondary growth for stem reinforcement) likely compensated for the increased light competition in Empetrum and Cassiope but did not avoid growth reduction in the shade intolerant Betula. The impact of warming and shading on shrub growth was more conservative. The lack of growth enhancement under warming suggests the absence of long-term acclimation for processes limiting biomass production. The lack of negative effects of shading on Cassiope was linked to morphological changes increasing the photosynthetic surface. Overall, tundra shrubs showed developmental plasticity over the longer term. However, such plasticity

  14. Species diversity modulates predation

    NARCIS (Netherlands)

    Kratina, P.; Vos, M.; Anholt, B.R.

    2007-01-01

    Predation occurs in a context defined by both prey and non-prey species. At present it is largely unknown how species diversity in general, and species that are not included in a predator's diet in particular, modify predator–prey interactions.Therefore we studied how both the density and diversity

  15. Prices and species diversity

    DEFF Research Database (Denmark)

    Sauer, Johannes

    of biodiversity and the appropriate incorporation in stochastic fron-tier models to achieve more realistic measures of production efficiency. We use the empirical example of tobacco production drawing from as well as affecting species diversity in the surrounding forests. We apply a shadow profit distance......In recent decades a significant amount of literature has been produced concerned with establishing a link between production efficiency and environmental efficiency with respect to quantitative modelling. This has been mainly addressed by focusing on the incorporation of undesirable outputs...... or the incorporation of environmentally det-rimental inputs. However, while the debate with respect to linear programming based DEA modelling is already at an advanced stage the corresponding one with respect to stochastic frontier modelling still needs considerable efforts. This contribution fo-cuses on the case...

  16. Off-season biogenic volatile organic compound emissions from heath mesocosms

    DEFF Research Database (Denmark)

    Rinnan, Riikka; Gierth, Diana; Bilde, Merete

    2013-01-01

    herbivory, mimicked by cutting the plants. Mesocosms from a temperate Deschampsia flexuosa-dominated heath ecosystem and a subarctic mixed heath ecosystem were either left intact, the aboveground vegetation was cut, or all plant parts (including roots) were removed. For 3-5 weeks, BVOC emissions were...... measured in growth chambers by an enclosure method using gas chromatography-mass spectrometry. CO2 exchange, soil microbial biomass and soil carbon and nitrogen concentrations were also analyzed. Vegetation cutting increased BVOC emissions by more than 20-fold, and the induced compounds were mainly eight...

  17. Species Diversity Enhances Predator Growth Rates

    International Nuclear Information System (INIS)

    Olson, M.H.; Jacobs, R.P.; O'Donnell, E.B.

    2007-01-01

    Predators can be important top-down regulators of community structure and are known to have both positive and negative effects on species diversity. However, little is known about the reciprocal effects of species diversity on predators. Across a set of 80 lakes in Connecticut, USA, we found a strong positive correlation between prey species diversity (using the Shannon-Weiner Diversity Index) and growth rates of largemouth bass (Micropterus salmoides). This correlation was strongest for small predators and decreased with body size. Although the underlying mechanisms are not known, the correlation is not driven by total fish abundance, predator abundance, or productivity.

  18. Heath Bunting / Heath Bunting ; interv. Tilman Baumgärtel

    Index Scriptorium Estoniae

    Bunting, Heath

    2006-01-01

    Inglise kunstnikust Heath Bunting'ust (sünd. 1966) ja tema loomingust, intervjuu kunstnikuga 19. VI 1997 Kasselis. H. Bunting tegelemisest grafitiga, oma Interneti-projektist "A visitor's guide to London", võrguprojektidest ja muust

  19. Off-season biogenic volatile organic compound emissions from heath mesocosms: responses to vegetation cutting.

    Science.gov (United States)

    Rinnan, Riikka; Gierth, Diana; Bilde, Merete; Rosenørn, Thomas; Michelsen, Anders

    2013-01-01

    Biogenic volatile organic compounds (BVOCs) affect both atmospheric processes and ecological interactions. Our primary aim was to differentiate between BVOC emissions from above- and belowground plant parts and heath soil outside the growing season. The second aim was to assess emissions from herbivory, mimicked by cutting the plants. Mesocosms from a temperate Deschampsia flexuosa-dominated heath ecosystem and a subarctic mixed heath ecosystem were either left intact, the aboveground vegetation was cut, or all plant parts (including roots) were removed. For 3-5 weeks, BVOC emissions were measured in growth chambers by an enclosure method using gas chromatography-mass spectrometry. CO2 exchange, soil microbial biomass, and soil carbon and nitrogen concentrations were also analyzed. Vegetation cutting increased BVOC emissions by more than 20-fold, and the induced compounds were mainly eight-carbon compounds and sesquiterpenes. In the Deschampsia heath, the overall low BVOC emissions originated mainly from soil. In the mixed heath, root, and soil emissions were negligible. Net BVOC emissions from roots and soil of these well-drained heaths do not significantly contribute to ecosystem emissions, at least outside the growing season. If insect outbreaks become more frequent with climate change, ecosystem BVOC emissions will periodically increase due to herbivory.

  20. Spatial patterns of species diversity in Kenya

    NARCIS (Netherlands)

    Oindo, B.O.

    2001-01-01

    The most striking feature of Earth is the existence of life and the most striking feature of life is its diversity. Explaining patterns of species diversity is one of the most complex problems in ecology. This is because diversity is usually the outcome of many contributing factors whose relative

  1. Species diversity of Trichoderma in Poland

    Science.gov (United States)

    Fifteen species of Trichoderma were identified from among 118 strains originating from different regions and ecological niches in Poland. This low number indicates low species diversity of Trichoderma in this Central European region. Using the ITS1-ITS2 regions, 64 strains were positively identified...

  2. SPECIES DIVERSITY AND STABILITY OF BIRD COMMUNITIES

    Directory of Open Access Journals (Sweden)

    Matsyura M.V.

    2011-12-01

    Full Text Available When comparing the suggested stability indicators, we obtained statistically significant correlations for indicators of annual stability of species and total number and standard deviation of the logarithm of the number. Annual Stability Index can be applied with a high degree of reliability as a characteristic of the averaged structure of the community and its pyramid of abundances. The results of correlation analysis confirm our assumptions about the correlation between stability over the years and indices of species diversity and relative uniformity.The final task of the study was to create a mathematical model of stability, where the independent variables are the indices of species diversity. The calculation of these indices allows forecasting birds’ community stability. According to the result of multiple regression for the indicators of diversity and stability of the breeding birds’ community highest correlation coefficients were obtained fro Shannon index and Simpson's dominance Index.Community stability could be determined by its overall species diversity. When considering the stability of community its diversity should be considered as a combination of uniformity of their total number and number of species. The most suitable predictors for the community stability were the nonparametric index of dominance and information-statistical indices, since they considered simultaneously evenness and richness. The community stability is subject of the complexity of its internal communications pattern.

  3. Variations in mountain vegetation use by reindeer (Rangifer tarandus) affects dry heath but not grass heath

    NARCIS (Netherlands)

    Moen, J.; Boogerd, C.; Skarin, A.

    2009-01-01

    Question: Are differences in landscape use of semi-domesticated reindeer reflected in the vegetation of summer grazing grounds? Location: Alpine heaths, central east Sweden. Methods: Dry heath and grass heath vegetation plots with inferred grazing intensities (high, intermediate and low) were

  4. Does species diversity limit productivity in natural grassland communities?

    NARCIS (Netherlands)

    Grace, James B.; Anderson, T. Michael; Smith, Melinda D.; Seabloom, Eric; Andelman, Sandy J.; Meche, Gayna; Weiher, Evan; Allain, Larry K.; Jutila, Heli; Sankaran, Mahesh; Knops, Johannes; Ritchie, Mark; Willig, Michael R.

    Theoretical analyses and experimental studies of synthesized assemblages indicate that under particular circumstances species diversity can enhance community productivity through niche complementarity. It remains unclear whether this process has important effects in mature natural ecosystems where

  5. Species diversity: Benthonic Foraminifera in Western North Atlantic

    Science.gov (United States)

    Buzas, M.A.; Gibson, T.G.

    1969-01-01

    Maximum species diversity occurs at abyssal depths of greater than 2500 meters. Other diversity peaks occur at depths of 35 to 45 meters and 100 to 200 meters. The peak at 35 to 45 meters is due to species equitability, whereas the other two peaks correspond to an increase in the number of species.

  6. Species Diversity and Growth Forms in Tropical American Palm Communities

    DEFF Research Database (Denmark)

    Balslev, Henrik; Kahn, Francis; Millán, Betty

    2011-01-01

    To advance our understanding of the processes that govern the assembly of palm communities and the local coexistence of numerous palm species, we here synthesize available information in the literature on species diversity and growth-form composition in palm communities across the Americas. Ameri...

  7. Remote sensing of species diversity using Landsat 8 spectral variables

    Science.gov (United States)

    Madonsela, Sabelo; Cho, Moses Azong; Ramoelo, Abel; Mutanga, Onisimo

    2017-11-01

    The application of remote sensing in biodiversity estimation has largely relied on the Normalized Difference Vegetation Index (NDVI). The NDVI exploits spectral information from red and near infrared bands of Landsat images and it does not consider canopy background conditions hence it is affected by soil brightness which lowers its sensitivity to vegetation. As such NDVI may be insufficient in explaining tree species diversity. Meanwhile, the Landsat program also collects essential spectral information in the shortwave infrared (SWIR) region which is related to plant properties. The study was intended to: (i) explore the utility of spectral information across Landsat-8 spectrum using the Principal Component Analysis (PCA) and estimate alpha diversity (α-diversity) in the savannah woodland in southern Africa, and (ii) define the species diversity index (Shannon (H‧), Simpson (D2) and species richness (S) - defined as number of species in a community) that best relates to spectral variability on the Landsat-8 Operational Land Imager dataset. We designed 90 m × 90 m field plots (n = 71) and identified all trees with a diameter at breast height (DbH) above 10 cm. H‧, D2 and S were used to quantify tree species diversity within each plot and the corresponding spectral information on all Landsat-8 bands were extracted from each field plot. A stepwise linear regression was applied to determine the relationship between species diversity indices (H‧, D2 and S) and Principal Components (PCs), vegetation indices and Gray Level Co-occurrence Matrix (GLCM) texture layers with calibration (n = 46) and test (n = 23) datasets. The results of regression analysis showed that the Simple Ratio Index derivative had a higher relationship with H‧, D2 and S (r2= 0.36; r2= 0.41; r2= 0.24 respectively) compared to NDVI, EVI, SAVI or their derivatives. Moreover the Landsat-8 derived PCs also had a higher relationship with H‧ and D2 (r2 of 0.36 and 0.35 respectively) than the

  8. Responses of vegetation and soil microbial communities to warming and simulated herbivory in a subarctic heath

    DEFF Research Database (Denmark)

    Rinnan, Riikka; Stark, Sari; Tolvanen, Anne

    2009-01-01

    Climate warming increases the cover of deciduous shrubs in arctic ecosystems and herbivory is also known to have a strong influence on the biomass and composition of vegetation. However, research combining herbivory with warming is largely lacking. Our study describes how warming and simulated...... setup of the International Tundra Experiment (ITEX). Wounding of the dominant deciduous dwarf shrub Vaccinium myrtillus L. to simulate herbivory was carried out annually. We measured vegetation cover in 2003 and 2007, soil nutrient concentrations in 2003 and 2006, soil microbial respiration in 2003...... and herbivory. 6 Synthesis. Our results show that warming increases the cover of V. myrtillus, which seems to enhance the nutrient sink strength of vegetation in the studied ecosystem. However, herbivory partially negates the effect of warming on plant N uptake and interacts with the effect of warming...

  9. Long-term warming and litter addition affects nitrogen fixation in a subarctic heath

    DEFF Research Database (Denmark)

    Sørensen, Pernille Lærkedal; Michelsen, Anders

    2011-01-01

    the measurements. We analyzed N fixation rates on both whole-ecosystem level and specifically on two moss species: Sphagnum warnstorfii and Hylocomium splendens. The whole-ecosystem N fixation of the warmed plots almost tripled compared with the control plots. However, in the Sphagnum and Hylocomium mosses we...

  10. Mineralization and carbon turnover in subarctic heath soil as affected by warming and additional litter

    DEFF Research Database (Denmark)

    Rinnan, Riikka; Michelsen, Anders; Baath, Erland

    2007-01-01

    Arctic soil carbon (C) stocks are threatened by the rapidly advancing global warming. In addition to temperature, increasing amounts of leaf litter fall following from the expansion of deciduous shrubs and trees in northern ecosystems may alter biogeochemical cycling of C and nutrients. Our aim w...... on C and N transformations during field incubation suggest that microbial activity is an important control on the carbon balance of arctic soils under climate change.......Arctic soil carbon (C) stocks are threatened by the rapidly advancing global warming. In addition to temperature, increasing amounts of leaf litter fall following from the expansion of deciduous shrubs and trees in northern ecosystems may alter biogeochemical cycling of C and nutrients. Our aim...

  11. The effect of organic farming systems on species diversity

    Science.gov (United States)

    Leksono, Amin Setyo

    2017-11-01

    Organic farming systems have been well known to support the diversity of a wide range of taxa, including microorganisms, arable flora, invertebrates, birds, and mammals, which benefit from organic management leading to increases in abundance and/or species richness. The objective of this paper is to review the effect of organic farming on species diversity reported in several articles and compare this with the current study in Gondanglegi, Malang. A review of several studies showed that organic farming systems have been reported to increase species diversity, including that of mammals, birds, arthropods, vascular plants and arbuscular mycorrhizal fungi. The researchers about arthropod groups consisted of carabid beetles, butterflies, wasps, predators, and bees. Agricultural landscape, habitat type, farming system, landscape composition and connectivity all contribute to explaining species biodiversity and richness. Moreover, based on current and relevant studies, the results showed that the application of refugia blocks has increased arthropod diversity and composition.

  12. Doubled volatile organic compound emissions from subarctic tundra under simulated climate warming.

    Science.gov (United States)

    Faubert, Patrick; Tiiva, Päivi; Rinnan, Asmund; Michelsen, Anders; Holopainen, Jarmo K; Rinnan, Riikka

    2010-07-01

    *Biogenic volatile organic compound (BVOC) emissions from arctic ecosystems are important in view of their role in global atmospheric chemistry and unknown feedbacks to global warming. These cold ecosystems are hotspots of climate warming, which will be more severe here than averaged over the globe. We assess the effects of climatic warming on non-methane BVOC emissions from a subarctic heath. *We performed ecosystem-based chamber measurements and gas chromatography-mass spectrometry (GC-MS) analyses of the BVOCs collected on adsorbent over two growing seasons at a wet subarctic tundra heath hosting a long-term warming and mountain birch (Betula pubescens ssp. czerepanovii) litter addition experiment. *The relatively low emissions of monoterpenes and sesquiterpenes were doubled in response to an air temperature increment of only 1.9-2.5 degrees C, while litter addition had a minor influence. BVOC emissions were seasonal, and warming combined with litter addition triggered emissions of specific compounds. *The unexpectedly high rate of release of BVOCs measured in this conservative warming scenario is far above the estimates produced by the current models, which underlines the importance of a focus on BVOC emissions during climate change. The observed changes have implications for ecological interactions and feedback effects on climate change via impacts on aerosol formation and indirect greenhouse effects.

  13. Genetic calibration of species diversity among North America's freshwater fishes

    OpenAIRE

    April, Julien; Mayden, Richard L.; Hanner, Robert H.; Bernatchez, Louis

    2011-01-01

    Freshwater ecosystems are being heavily exploited and degraded by human activities all over the world, including in North America, where fishes and fisheries are strongly affected. Despite centuries of taxonomic inquiry, problems inherent to species identification continue to hamper the conservation of North American freshwater fishes. Indeed, nearly 10% of species diversity is thought to remain undescribed. To provide an independent calibration of taxonomic uncertainty and to establish a mor...

  14. Satellite lakes as reservoirs of fish species diversity

    OpenAIRE

    Nkalubo, W.; Wandera, S.B.; Namulemo, G.

    2010-01-01

    Satellite lakes and rivers in the Victoria and Kyoga basins provide a sanctuary for endangered native fish species. The structural heterogeneity of macrophyte covering these lakes has made it possible for most of the biodiversity to be kept intact. The Kyoga minor lakes have the highest fish species diversity especially of the haplochromines. Most fish communities of these satellite lakes are composed of native species.

  15. Weed species diversity in organic and integrated farming systems

    Directory of Open Access Journals (Sweden)

    Magdalena Jastrzębska

    2013-10-01

    Full Text Available Phytosociological data were collected in 1994–1996 in plots (relevés at the Research Station for Organic Farming and Conservation Breeding of the Polish Academy of Sciences in Popielno included in a large-area experiment conducted according to the concept and method proposed by Prof. S. Nawrocki. In a four-field crop rotation (root crops – spring barley undersown with red clover and grasses – red clover/grass mixture – winter triticale, each field was divided into two management units, organic and integrated. Data were collected in relevés by the Braun-Blanquet method, each year at the peak of the growing season. Weed abundance (% cover in cultivated fields and the number of weed species (species richness in crops were determined, which provided a basis for calculating the Shannon-Wiener indices of species diversity and evenness, and the Rényi profiles. The qualitative (species and quantitative structure of weed communities was compared using the Sørensen index. A total of 115 weed taxa (species, subspecies and varieties were identified in the examined agro-phytocenoses. Echinochloa crus-galli, Chenopodium album, Matricaria maritima subsp. inodora, Capsella bursa-pastoris, Thlaspi arvense and Stellaria media were the most abundant. Weed infestation was slightly higher in the organic farming system than in the integrated system. Organic farming contributed to higher weed species diversity in root crops, red clover/grass mixtures and winter triticale. Weed species richness was reduced in red clover/grass stands, while root crops and – to a lesser degree – spring barley undersown with red clover and grasses decreased weed species diversity. The species composition and in particular the quantitative structure of weeds were affected by crop species and cultivation regime rather than by the farming system. Weed communities of crops grown under organic and integrated farming systems were more similar with regard to species composition

  16. Genetic calibration of species diversity among North America's freshwater fishes.

    Science.gov (United States)

    April, Julien; Mayden, Richard L; Hanner, Robert H; Bernatchez, Louis

    2011-06-28

    Freshwater ecosystems are being heavily exploited and degraded by human activities all over the world, including in North America, where fishes and fisheries are strongly affected. Despite centuries of taxonomic inquiry, problems inherent to species identification continue to hamper the conservation of North American freshwater fishes. Indeed, nearly 10% of species diversity is thought to remain undescribed. To provide an independent calibration of taxonomic uncertainty and to establish a more accessible molecular identification key for its application, we generated a standard reference library of mtDNA sequences (DNA barcodes) derived from expert-identified museum specimens for 752 North American freshwater fish species. This study demonstrates that 90% of known species can be delineated using barcodes. Moreover, it reveals numerous genetic discontinuities indicative of independently evolving lineages within described species, which points to the presence of morphologically cryptic diversity. From the 752 species analyzed, our survey flagged 138 named species that represent as many as 347 candidate species, which suggests a 28% increase in species diversity. In contrast, several species of parasitic and nonparasitic lampreys lack such discontinuity and may represent alternative life history strategies within single species. Therefore, it appears that the current North American freshwater fish taxonomy at the species level significantly conceals diversity in some groups, although artificially creating diversity in others. In addition to providing an easily accessible digital identification system, this study identifies 151 fish species for which taxonomic revision is required.

  17. An exactly solvable coarse-grained model for species diversity

    Science.gov (United States)

    Suweis, Samir; Rinaldo, Andrea; Maritan, Amos

    2012-07-01

    We present novel analytical results concerning ecosystem species diversity that stem from a proposed coarse-grained neutral model based on birth-death processes. The relevance of the problem lies in the urgency for understanding and synthesizing both theoretical results from ecological neutral theory and empirical evidence on species diversity preservation. The neutral model of biodiversity deals with ecosystems at the same trophic level, where per capita vital rates are assumed to be species independent. Closed-form analytical solutions for the neutral theory are obtained within a coarse-grained model, where the only input is the species persistence time distribution. Our results pertain to: the probability distribution function of the number of species in the ecosystem, both in transient and in stationary states; the n-point connected time correlation function; and the survival probability, defined as the distribution of time spans to local extinction for a species randomly sampled from the community. Analytical predictions are also tested on empirical data from an estuarine fish ecosystem. We find that emerging properties of the ecosystem are very robust and do not depend on specific details of the model, with implications for biodiversity and conservation biology.

  18. An exactly solvable coarse-grained model for species diversity

    International Nuclear Information System (INIS)

    Suweis, Samir; Maritan, Amos; Rinaldo, Andrea

    2012-01-01

    We present novel analytical results concerning ecosystem species diversity that stem from a proposed coarse-grained neutral model based on birth–death processes. The relevance of the problem lies in the urgency for understanding and synthesizing both theoretical results from ecological neutral theory and empirical evidence on species diversity preservation. The neutral model of biodiversity deals with ecosystems at the same trophic level, where per capita vital rates are assumed to be species independent. Closed-form analytical solutions for the neutral theory are obtained within a coarse-grained model, where the only input is the species persistence time distribution. Our results pertain to: the probability distribution function of the number of species in the ecosystem, both in transient and in stationary states; the n-point connected time correlation function; and the survival probability, defined as the distribution of time spans to local extinction for a species randomly sampled from the community. Analytical predictions are also tested on empirical data from an estuarine fish ecosystem. We find that emerging properties of the ecosystem are very robust and do not depend on specific details of the model, with implications for biodiversity and conservation biology. (paper)

  19. Birds' species diversity measurement of Uchali Wetland (Ramsar site Pakistan

    Directory of Open Access Journals (Sweden)

    Taofik Oyedele Dauda

    2017-06-01

    Full Text Available We carried out this study to evaluate bird species diversity and to model bird species abundance using Uchali Wetland, Pakistan (32°33′N, 72°01′E. Data obtained were subjected to summary statistics, Simpson diversity, Shannon evenness index, and rank abundance curve and model. The watershed supports 25,361 birds of 47 species, which is appreciably less than the number of bird species supported by the same wetland in the past year (1991. Total evenness could be obtained as the ranks increases and this differed annually. Evenness index (EI analysis showed that EI for 2011 was 0.0231, for 2012, it was 0.02, for 2013, it was 0.01, and for the annual mean, it was 0.046 indicating functional abundance of the species. Bird species diversity measurement could be enhanced by the use of the modified rank–abundance curve and would clearly present the true picture of the bird species abundance.

  20. Ecological mechanisms underlying arthropod species diversity in grasslands.

    Science.gov (United States)

    Joern, Anthony; Laws, Angela N

    2013-01-01

    Arthropods are an important component of grassland systems, contributing significantly to biodiversity and ecosystem structure and function. Climate, fire, and grazing by large herbivores are important drivers in grasslands worldwide. Arthropod responses to these drivers are highly variable and clear patterns are difficult to find, but responses are largely indirect with respect to changes in resources, species interactions, habitat structure, and habitat heterogeneity resulting from interactions among fire, grazing, and climate. Here, we review these ecological mechanisms influencing grassland arthropod diversity. We summarize hypotheses describing species diversity at local and regional scales and then discuss specific factors that may affect arthropod diversity in grassland systems. These factors include direct and indirect effects of grazing, fire, and climate, species interactions, above- and belowground interactions, and landscape-level effects.

  1. High-Resolution Remote Sensing and Stable Isotope Patterns Across Heath-Shrub-Forest Ecotone at Abisko and Vassijaure, Northern Sweden

    Science.gov (United States)

    Schwan, M. R.; Herrick, C.; Hobbie, E. A.; Chen, J.; Varner, R. K.; Palace, M. W.; Marek, E.; Kashi, N. N.; Smith, S. L.

    2015-12-01

    Rapid warming in arctic and sub-arctic environments shifts plant community structure which in turn can alter carbon cycling by releasing large stocks of carbon sequestered in arctic soils. Much work has been done in sub-arctic peatlands to understand how shifts in dominant vegetation cover can ultimately affect global carbon balances, but less focus has been given to upland environments where similar changes are occurring. Recent circumpolar expansion of deciduous shrubs and trees in sub-arctic upland environments may alter carbon cycling due to shrubs and trees sequestering less C in soils than the heath plants they typically replace. In this study we explored the relationship between nutrient and carbon cycling and above-ground vegetation on six transects which traverse an ecotone gradient from heath tundra (dominated by ericoid mycorrhizal plants) through deciduous shrubs to deciduous trees (dominated by ectomycorrhizal plants) in upland environments of sub-arctic Sweden near Vassijaure (~850 mm precipitation) and Abisko (~300 mm precipitation). We collected soil and foliage for analysis of natural abundances of stable carbon and nitrogen isotopes (δ13C and δ15N), which can be a sensitive indicator of C and N dynamics. We also took high-resolution remote aerial imagery over the transects to calculate percent cover of vegetation types using GIS software. We concurrently estimated percent cover in smaller plots on the ground of three dominant species, Empetrum nigrum, Betula nana, and Betula pubescens, to serve as ground-truthing for the aerial imagery. Analysis of vegetation cover data shows significant differences in vegetation types along the transects. Preliminary multiple regression analysis of isotopes shows that δ13C in organic soil at the Vassijaure site is mostly controlled by distance along the transect, an interaction term between transect distance and soil depth, and δ15N (adjusted r2 = 0.85, p regression analyses, δ15N was primarily controlled by

  2. Responses of non-methane biogenic volatile organic compound emissions to climate change in boreal and subarctic ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Faubert, P.

    2010-07-01

    Non-methane biogenic volatile organic compound emissions (BVOCs) have important roles in the global atmospheric chemistry but their feedbacks to climate change are still unknown. This thesis reports one of the first estimates of BVOC emissions from boreal and subarctic ecosystems. Most importantly, this thesis assesses the BVOC emission responses to four effects of climate change in these ecosystems: (1) the direct effect of warming, and its indirect effects via (2) water table drawdown, (3) change in the vegetation composition, and (4) enhanced UV-B radiation. BVOC emissions were measured using a conventional chamber method in which the compounds were collected on adsorbent and later analyzed by gas chromatography-mass spectrometry. On a subarctic heath, warming by only 1.9-2.5 degC doubled the monoterpene and sesquiterpene emissions. Such a high increase of BVOC emissions under a conservative warming cannot be predicted by the current models, which underlines the importance of a focus on BVOC emissions from the Subarctic under climate change. On a subarctic peatland, enhanced UV-B did not affect the BVOC emissions but the water table level exerted the major effect. The water table drawdown experimentally applied on boreal peatland microcosms decreased the emissions of monoterpenes and other VOCs (BVOCs with a lifetime>1 d) for the hollows (wet microsites) and that of all BVOC groups for the lawns (moderately wet microsites). The warming treatment applied on the lawn microcosms decreased the isoprene emission. The removal of vascular plants in the hummock (dry microsites) microcosms decreased the emissions of monoterpenes while the emissions between the microcosms covered with Sphagnum moss and bare peat were not different. In conclusion, the results presented in this thesis indicate that climate change has complex effects on the BVOC emissions. These results make a significant contribution to improving the modeling of BVOC emissions for a better understanding of

  3. RiverHeath: Neighborhood Loop Geothermal Exchange System

    Energy Technology Data Exchange (ETDEWEB)

    Geall, Mark [RiverHeath LLC, Appleton, WI (United States)

    2016-07-11

    The goal of the RiverHeath project is to develop a geothermal exchange system at lower capital infrastructure cost than current geothermal exchange systems. The RiverHeath system features an innovative design that incorporates use of the adjacent river through river-based heat exchange plates. The flowing water provides a tremendous amount of heat transfer. As a result, the installation cost of this geothermal exchange system is lower than more traditional vertical bore systems. Many urban areas are located along rivers and other waterways. RiverHeath will serve as a template for other projects adjacent to the water.

  4. Species Diversity and Bird Feed in Residential Complex

    Science.gov (United States)

    Hadinoto; Suhesti, Eni

    2017-12-01

    Bird is one component of the ecosystem which has an important role in supporting the occurrence of an organism's life cycle. Therefore, the presence of birds in an area is important, because it can affect the existence and distribution of plant species. The purpose of this study is to calculate the diversity of bird species and identify the source of bird feed in the compound. This study was conducted by field surveys in the residential complex. In addition to the birds as a research object vegetation as habitat / foraging birds were also observed. Data were analyzed by using the bird diversity index, richenes index, bundance index, dominance analysis, analysis of bird distribution and analysis of the level of meeting types, while vegetation will be analyzed based on the type and part of what is eaten by birds. In Pandau Jaya housing complex, found as many as 12 species of birds which consists of seven families. Bird species often present is Cucak Kutilang (Pycnonotus aurigaster) of 20 individuals, Bondol Peking (Lonchura punctulata) 14 individuals and Perkutut Jawa (Geopelia striata) 10 individuals. Bird species diversity (H ‘) in Pandau Jaya housing complex is still relatively moderate with a value of 2.27, while the Evenness Index (E) of 0.91 and Richenes Index (R) of 2.45. Types of vegetation as a food source, among others: mango, guava, cherry, jackfruit, ketapang, coconut, areca, palm, banana, papaya, flowers and grasses.

  5. [Species diversity of ex-situ cultivated Chinese medicinal plants].

    Science.gov (United States)

    Que, Ling; Chi, Xiu-Lian; Zang, Chun-Xin; Zhang, Yu; Chen, Min; Yang, Guang; Jin, An-Qi

    2018-03-01

    Ex-situ conservation is an important means to protect biological genetic resources. Resource protection has received more and more attention with the continuous improvement of the comprehensive utilization of traditional Chinese medicine resources. In this paper, the research and compilation of the species list of ex-situ cultivated medicinal plants in 12 Chinese Academy of Sciences botanic gardens and 19 specialized medicinal botanic gardens in China were carried out. Based on the Species 2000(2017) and other classification databases, species diversity of medicinal plants ex-situ cultivated in these botanical gardens were analyzed. The study found that there were 16 351 higher plant species in our country, belonging to 276 families and 1 936 genera. Of these, 6 949 specieswere medicinal plants, accounting for 50.4% of the total medicinal plants. There were 1 280 medicinal plants were in threatened status, accounting for 19.6% of all threatened species in the Chinese Biodiversity Red List, with ex-situ cultivated proportion of 59.5%. And 3 988 medicinal plants were Chinese endemic species, accounting for 22.5% of all Chinese endemic species, with ex-situ cultivated proportion of 53.3%. This article has reference significance for the management and protection of medicinal plant resources. Copyright© by the Chinese Pharmaceutical Association.

  6. Phylogenetically diverse macrophyte community promotes species diversity of mobile epi-benthic invertebrates

    Science.gov (United States)

    Nakamoto, Kenta; Hayakawa, Jun; Kawamura, Tomohiko; Kodama, Masafumi; Yamada, Hideaki; Kitagawa, Takashi; Watanabe, Yoshiro

    2018-07-01

    Various aspects of plant diversity such as species diversity and phylogenetic diversity enhance the species diversity of associated animals in terrestrial systems. In marine systems, however, the effects of macrophyte diversity on the species diversity of associated animals have received little attention. Here, we sampled in a subtropical seagrass-seaweed mixed bed to elucidate the effect of the macrophyte phylogenetic diversity based on the taxonomic relatedness as well as the macrophyte species diversity on species diversity of mobile epi-benthic invertebrates. Using regression analyses for each macrophyte parameter as well as multiple regression analyses, we found that the macrophyte phylogenetic diversity (taxonomic diversity index: Delta) positively influenced the invertebrate species richness and diversity index (H‧). Although the macrophyte species richness and H‧ also positively influenced the invertebrate species richness, the best fit model for invertebrate species richness did not include them, suggesting that the macrophyte species diversity indirectly influenced invertebrate species diversity. Possible explanations of the effects of macrophyte Delta on the invertebrate species diversity were the niche complementarity effect and the selection effect. This is the first study which demonstrates that macrophyte phylogenetic diversity has a strong effect on the species diversity of mobile epi-benthic invertebrates.

  7. Neotropical bats: estimating species diversity with DNA barcodes.

    Directory of Open Access Journals (Sweden)

    Elizabeth L Clare

    Full Text Available DNA barcoding using the cytochrome c oxidase subunit 1 gene (COI is frequently employed as an efficient method of species identification in animal life and may also be used to estimate species richness, particularly in understudied faunas. Despite numerous past demonstrations of the efficiency of this technique, few studies have attempted to employ DNA barcoding methodologies on a large geographic scale, particularly within tropical regions. In this study we survey current and potential species diversity using DNA barcodes with a collection of more than 9000 individuals from 163 species of Neotropical bats (order Chiroptera. This represents one of the largest surveys to employ this strategy on any animal group and is certainly the largest to date for land vertebrates. Our analysis documents the utility of this tool over great geographic distances and across extraordinarily diverse habitats. Among the 163 included species 98.8% possessed distinct sets of COI haplotypes making them easily recognizable at this locus. We detected only a single case of shared haplotypes. Intraspecific diversity in the region was high among currently recognized species (mean of 1.38%, range 0-11.79% with respect to birds, though comparable to other bat assemblages. In 44 of 163 cases, well-supported, distinct intraspecific lineages were identified which may suggest the presence of cryptic species though mean and maximum intraspecific divergence were not good predictors of their presence. In all cases, intraspecific lineages require additional investigation using complementary molecular techniques and additional characters such as morphology and acoustic data. Our analysis provides strong support for the continued assembly of DNA barcoding libraries and ongoing taxonomic investigation of bats.

  8. Climate change-induced vegetation change as a driver of increased subarctic biogenic volatile organic compound emissions.

    Science.gov (United States)

    Valolahti, Hanna; Kivimäenpää, Minna; Faubert, Patrick; Michelsen, Anders; Rinnan, Riikka

    2015-09-01

    Emissions of biogenic volatile organic compounds (BVOCs) have been earlier shown to be highly temperature sensitive in subarctic ecosystems. As these ecosystems experience rapidly advancing pronounced climate warming, we aimed to investigate how warming affects the BVOC emissions in the long term (up to 13 treatment years). We also aimed to assess whether the increased litterfall resulting from the vegetation changes in the warming subarctic would affect the emissions. The study was conducted in a field experiment with factorial open-top chamber warming and annual litter addition treatments on subarctic heath in Abisko, northern Sweden. After 11 and 13 treatment years, BVOCs were sampled from plant communities in the experimental plots using a push-pull enclosure technique and collection into adsorbent cartridges during the growing season and analyzed with gas chromatography-mass spectrometry. Plant species coverage in the plots was analyzed by the point intercept method. Warming by 2 °C caused a 2-fold increase in monoterpene and 5-fold increase in sesquiterpene emissions, averaged over all measurements. When the momentary effect of temperature was diminished by standardization of emissions to a fixed temperature, warming still had a significant effect suggesting that emissions were also indirectly increased. This indirect increase appeared to result from increased plant coverage and changes in vegetation composition. The litter addition treatment also caused significant increases in the emission rates of some BVOC groups, especially when combined with warming. The combined treatment had both the largest vegetation changes and the highest BVOC emissions. The increased emissions under litter addition were probably a result of a changed vegetation composition due to alleviated nutrient limitation and stimulated microbial production of BVOCs. We suggest that the changes in the subarctic vegetation composition induced by climate warming will be the major factor

  9. Soil phosphorus heterogeneity promotes tree species diversity and phylogenetic clustering in a tropical seasonal rainforest.

    Science.gov (United States)

    Xu, Wumei; Ci, Xiuqin; Song, Caiyun; He, Tianhua; Zhang, Wenfu; Li, Qiaoming; Li, Jie

    2016-12-01

    The niche theory predicts that environmental heterogeneity and species diversity are positively correlated in tropical forests, whereas the neutral theory suggests that stochastic processes are more important in determining species diversity. This study sought to investigate the effects of soil nutrient (nitrogen and phosphorus) heterogeneity on tree species diversity in the Xishuangbanna tropical seasonal rainforest in southwestern China. Thirty-nine plots of 400 m 2 (20 × 20 m) were randomly located in the Xishuangbanna tropical seasonal rainforest. Within each plot, soil nutrient (nitrogen and phosphorus) availability and heterogeneity, tree species diversity, and community phylogenetic structure were measured. Soil phosphorus heterogeneity and tree species diversity in each plot were positively correlated, while phosphorus availability and tree species diversity were not. The trees in plots with low soil phosphorus heterogeneity were phylogenetically overdispersed, while the phylogenetic structure of trees within the plots became clustered as heterogeneity increased. Neither nitrogen availability nor its heterogeneity was correlated to tree species diversity or the phylogenetic structure of trees within the plots. The interspecific competition in the forest plots with low soil phosphorus heterogeneity could lead to an overdispersed community. However, as heterogeneity increase, more closely related species may be able to coexist together and lead to a clustered community. Our results indicate that soil phosphorus heterogeneity significantly affects tree diversity in the Xishuangbanna tropical seasonal rainforest, suggesting that deterministic processes are dominant in this tropical forest assembly.

  10. Genetic diversity and species diversity of stream fishes covary across a land-use gradient

    Science.gov (United States)

    Blum, M.J.; Bagley, M.J.; Walters, D.M.; Jackson, S.A.; Daniel, F.B.; Chaloud, D.J.; Cade, B.S.

    2012-01-01

    Genetic diversity and species diversity are expected to covary according to area and isolation, but may not always covary with environmental heterogeneity. In this study, we examined how patterns of genetic and species diversity in stream fishes correspond to local and regional environmental conditions. To do so, we compared population size, genetic diversity and divergence in central stonerollers (Campostoma anomalum) to measures of species diversity and turnover in stream fish assemblages among similarly sized watersheds across an agriculture-forest land-use gradient in the Little Miami River basin (Ohio, USA). Significant correlations were found in many, but not all, pair-wise comparisons. Allelic richness and species richness were strongly correlated, for example, but diversity measures based on allele frequencies and assemblage structure were not. In-stream conditions related to agricultural land use were identified as significant predictors of genetic diversity and species diversity. Comparisons to population size indicate, however, that genetic diversity and species diversity are not necessarily independent and that variation also corresponds to watershed location and glaciation history in the drainage basin. Our findings demonstrate that genetic diversity and species diversity can covary in stream fish assemblages, and illustrate the potential importance of scaling observations to capture responses to hierarchical environmental variation. More comparisons according to life history variation could further improve understanding of conditions that give rise to parallel variation in genetic diversity and species diversity, which in turn could improve diagnosis of anthropogenic influences on aquatic ecosystems. ?? 2011 Springer-Verlag.

  11. Estimating tree species diversity in the savannah using NDVI and woody canopy cover

    Science.gov (United States)

    Madonsela, Sabelo; Cho, Moses Azong; Ramoelo, Abel; Mutanga, Onisimo; Naidoo, Laven

    2018-04-01

    Remote sensing applications in biodiversity research often rely on the establishment of relationships between spectral information from the image and tree species diversity measured in the field. Most studies have used normalized difference vegetation index (NDVI) to estimate tree species diversity on the basis that it is sensitive to primary productivity which defines spatial variation in plant diversity. The NDVI signal is influenced by photosynthetically active vegetation which, in the savannah, includes woody canopy foliage and grasses. The question is whether the relationship between NDVI and tree species diversity in the savanna depends on the woody cover percentage. This study explored the relationship between woody canopy cover (WCC) and tree species diversity in the savannah woodland of southern Africa and also investigated whether there is a significant interaction between seasonal NDVI and WCC in the factorial model when estimating tree species diversity. To fulfil our aim, we followed stratified random sampling approach and surveyed tree species in 68 plots of 90 m × 90 m across the study area. Within each plot, all trees with diameter at breast height of >10 cm were sampled and Shannon index - a common measure of species diversity which considers both species richness and abundance - was used to quantify tree species diversity. We then extracted WCC in each plot from existing fractional woody cover product produced from Synthetic Aperture Radar (SAR) data. Factorial regression model was used to determine the interaction effect between NDVI and WCC when estimating tree species diversity. Results from regression analysis showed that (i) WCC has a highly significant relationship with tree species diversity (r2 = 0.21; p NDVI and WCC is not significant, however, the factorial model significantly reduced the error of prediction (RMSE = 0.47, p NDVI (RMSE = 0.49) or WCC (RMSE = 0.49) model during the senescence period. The result justifies our assertion

  12. Rapid carbon turnover beneath shrub and tree vegetation is associated with low soil carbon stocks at a subarctic treeline.

    Science.gov (United States)

    Parker, Thomas C; Subke, Jens-Arne; Wookey, Philip A

    2015-05-01

    Climate warming at high northern latitudes has caused substantial increases in plant productivity of tundra vegetation and an expansion of the range of deciduous shrub species. However significant the increase in carbon (C) contained within above-ground shrub biomass, it is modest in comparison with the amount of C stored in the soil in tundra ecosystems. Here, we use a 'space-for-time' approach to test the hypothesis that a shift from lower-productivity tundra heath to higher-productivity deciduous shrub vegetation in the sub-Arctic may lead to a loss of soil C that out-weighs the increase in above-ground shrub biomass. We further hypothesize that a shift from ericoid to ectomycorrhizal systems coincident with this vegetation change provides a mechanism for the loss of soil C. We sampled soil C stocks, soil surface CO2 flux rates and fungal growth rates along replicated natural transitions from birch forest (Betula pubescens), through deciduous shrub tundra (Betula nana) to tundra heaths (Empetrum nigrum) near Abisko, Swedish Lapland. We demonstrate that organic horizon soil organic C (SOCorg ) is significantly lower at shrub (2.98 ± 0.48 kg m(-2) ) and forest (2.04 ± 0.25 kg m(-2) ) plots than at heath plots (7.03 ± 0.79 kg m(-2) ). Shrub vegetation had the highest respiration rates, suggesting that despite higher rates of C assimilation, C turnover was also very high and less C is sequestered in the ecosystem. Growth rates of fungal hyphae increased across the transition from heath to shrub, suggesting that the action of ectomycorrhizal symbionts in the scavenging of organically bound nutrients is an important pathway by which soil C is made available to microbial degradation. The expansion of deciduous shrubs onto potentially vulnerable arctic soils with large stores of C could therefore represent a significant positive feedback to the climate system. © 2014 John Wiley & Sons Ltd.

  13. Plant species diversity affects infiltration capacity in an experimental grassland through changes in soil properties

    NARCIS (Netherlands)

    Fischer, C.; Tischer, J.; Roscher, C.; Eisenhauer, N.; Ravenek, J.; Gleixner, G.; Attinger, S.; Jensen, B.; Kroon, de H.; Mommer, L.; Scheu, S.; Hildebrandt, A.

    2015-01-01

    Background and aims Soil hydraulic properties drive water distribution and availability in soil. There exists limited knowledge of how plant species diversity might influence soil hydraulic properties. Methods We quantified the change in infiltration capacity affected by soil structural variables

  14. Estimating tree species diversity in the savannah using NDVI and woody canopy cover

    CSIR Research Space (South Africa)

    Madonsela, Sabelo

    2018-04-01

    Full Text Available Remote sensing applications in biodiversity research often rely on the establishment of relationships between spectral information from the image and tree species diversity measured in the field. Most studies have used normalized difference...

  15. Pest species diversity enhances control of spider mites and whiteflies by a generalist phytoseiid predator

    NARCIS (Netherlands)

    Messelink, G.J.; Maanen, van R.; Holstein-Saj, van R.; Sabelis, M.W.; Janssen, A.

    2010-01-01

    To test the hypothesis that pest species diversity enhances biological pest control with generalist predators, we studied the dynamics of three major pest species on greenhouse cucumber: Western flower thrips, Frankliniella occidentalis (Pergande), greenhouse whitefly, Trialeurodes vaporariorum

  16. Species diversity and abundance of wild birds in Dagona-Waterfowl ...

    African Journals Online (AJOL)

    hope&shola

    The study of bird species diversity and richness in Dagona-Waterfowl sanctuary was carried out in early wet and late dry ... conservation of important species that rural inhabitants ... wetland of international importance on waterfowl habitat,.

  17. Effects of litter addition and warming on soil carbon, nutrient pools and microbial communities in a subarctic heath ecosystem

    DEFF Research Database (Denmark)

    Rinnan, Riikka; Michelsen, Anders; Jonasson, Sven Evert

    2008-01-01

    in the uppermost 5 cm soil, while decreasing the pool of total P per unit area of the organic profile and having no significant effects on N concentrations or pools. Microbial biomass C and N were unaffected by the treatments, while the microbial biomass P increased significantly with litter addition. Soil...... proportion of biomarkers for Gram-positive bacteria. The combined warming plus litter addition treatment decreased the soil water content in the uppermost 5 cm soil, which was a likely reason for many interactions between the effects of warming and litter addition. The soil organic matter quality...... of the combined treatment was also clearly different from the control based on a near-infrared reflectance (NIR) spectroscopic analysis, implying that the treatment altered the composition of soil organic matter. However, it appears that the biological processes and the microbial community composition responded...

  18. Freeze-thaw regime effects on carbon and nitrogen dynamics in sub-arctic heath tundra mesocosms

    DEFF Research Database (Denmark)

    Grogan, P.; Michelsen, A.; Ambus, P.

    2004-01-01

    phase, and in a subsequent equilibration phase. A single deep freeze treatment phase enhanced dissolved total and labelled N pools in the soil solution at initial thaw, and resulted in reduced pool sizes at the end of the equilibration phase. By contrast, a multiple freeze-thaw cycling treatment......, these results indicate that moderate freeze-thaw fluctuations may have minimal influences on microbial biomass pools, but nevertheless can have strong contrasting effects on the amounts, forms, and timing of N and organic C supply into the soil solution. Ecosystem losses via N2O effluxes were of greatest...... directly enhanced the dissolved labelled N pool, but did not significantly affect dissolved total N. Furthermore, both dissolved labelled N and dissolved total N pools were significantly enhanced in the equilibration period following multiple freeze-thaw, the latter due to a marked increase in soil...

  19. Agroforestry parkland species diversity : uses and management in semi-arid West-Africa (Burkina Faso)

    OpenAIRE

    Nikiema, A.

    2005-01-01

    Agroforestry parkland in semi-arid West Africa is a rural land use system, which allows farmers to grow annual crops in combination with useful trees. In addition to cereals, tree products such as vegetables, fruits, vegetable oil, firewood, fodder, and medicines are obtained from the parklands. However the multiple function of the parkland system can only be fulfilled if parkland species diversity is adequately managed.This thesis is focused on assessing the woody species diversity in the pa...

  20. Species Diversity of Shallow Water Zoanthids (Cnidaria: Anthozoa: Hexacorallia) in Florida

    OpenAIRE

    Reimer, James Davis; Foord, Colin; Irei, Yuka

    2012-01-01

    Shallow water zooxanthellate zoanthids are a common component of the coral reef ecosystems of the Caribbean. Despite this, their species diversity remains poorly understood. In this study, collected Palythoa, Zoanthus, Isaurus, and Terrazoanthus specimens from the waters of Florida were phylogenetically examined to obtain a better understanding of zoanthid species diversity in the Caribbean. Surprisingly, the results from analyses utilizing three DNA markers (mitochondrial 16S ribosomal DNA, ...

  1. Phytogeographical relations in the North West European heath

    NARCIS (Netherlands)

    Smidt, de J.T.

    1967-01-01

    The water economy, the mineral content of the soil, and human influence are the principal ecological factors governing the variation of the heath vegetation of a limited region. Sloping of the surface is also an important factor. In hilly country it is of a twofold nature: on the one hand the

  2. 2015-2016 Expense report for Alanna Heath | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2015-07-13

    2015-2016 Expense report for Alanna Heath. Total travel expenses: CA$912.20. Board meetings. July 13, 2015 to July 14, 2015. CA$912.20. What we do · Funding · Resources · About IDRC. Knowledge. Innovation. Solutions. Careers · Contact Us · Site map. Sign up now for IDRC news and views sent directly to your inbox ...

  3. Heath Ledgeri viimane film tehakse lõpuni

    Index Scriptorium Estoniae

    2008-01-01

    Terry Gilliam teatas, et jätkab võtteid mängufilmi "The Imaginarium of Doctor Parnassus" lõpetamiseks (film jäi näitleja Heath Ledgeri surma tõttu pooleli), lastes tema rolli esitada kolmel väljapaistval näitlejal (Johnny Depp, Colin Farrell, Jude Law)

  4. Temperature and substrate controls on intra-annual variation in ecosystem respiration in two subarctic vegetation types

    DEFF Research Database (Denmark)

    Grogan, Paul; Jonasson, Sven Evert

    2005-01-01

    significantly to ecosystem respiration during most phases of winter and summer in the two vegetation types. Ecosystem respiration rates through the year did not differ significantly between vegetation types despite substantial differences in biomass pools, soil depth and temperature regime. Most (76...... contributions of bulk soil organic matter and plant-associated carbon pools to ecosystem respiration is critical to predicting the response of arctic ecosystem net carbon balance to climate change. In this study, we determined the variation in ecosystem respiration rates from birch forest understory and heath......-92%) of the intra-annual variation in ecosystem respiration rates from these two common mesic subarctic ecosystems was explained using a first-order exponential equation relating respiration to substrate chemical quality and soil temperature. Removal of plants and their current year's litter significantly reduced...

  5. Genetic diversity within a dominant plant outweighs plant species diversity in structuring an arthropod community.

    Science.gov (United States)

    Crawford, Kerri M; Rudgers, Jennifer A

    2013-05-01

    Plant biodiversity is being lost at a rapid rate. This has spurred much interest in elucidating the consequences of this loss for higher trophic levels. Experimental tests have shown that both plant species diversity and genetic diversity within a plant species can influence arthropod community structure. However, the majority of these studies have been conducted in separate systems, so their relative importance is currently unresolved. Furthermore, potential interactions between the two levels of diversity, which likely occur in natural systems, have not been investigated. To clarify these issues, we conducted three experiments in a freshwater sand dune ecosystem. We (1) independently manipulated plant species diversity, (2) independently manipulated genetic diversity within the dominant plant species, Ammophila breviligulata, and (3) jointly manipulated genetic diversity within the dominant plant and species diversity. We found that genetic diversity within the dominant plant species, Ammophila breviligulata, more strongly influenced arthropod communities than plant species diversity, but this effect was dependent on the presence of other species. In species mixtures, A. breviligulata genetic diversity altered overall arthropod community composition, and arthropod richness and abundance peaked at the highest level of genetic diversity. Positive nonadditive effects of diversity were detected, suggesting that arthropods respond to emergent properties of diverse plant communities. However, in the independent manipulations where A. breviligulata was alone, effects of genetic diversity were weaker, with only arthropod richness responding. In contrast, plant species diversity only influenced arthropods when A. breviligulata was absent, and then only influenced herbivore abundance. In addition to showing that genetic diversity within a dominant plant species can have large effects on arthropod community composition, these results suggest that understanding how species

  6. Comparative responses of phenology and reproductive development to simulated environmental change in sub-arctic and high arctic plants

    Energy Technology Data Exchange (ETDEWEB)

    Wookey, P A; Welker, J M; Callaghan, T V [Inst. of Terrestrial Ecology, Merlewood Research Station, Grange-over-Sands, Cumbria (United Kingdom); Parsons, A N; Potter, J A; Lee, J A; Press, M C [Dept. of Environmental Biology, Univ. of Manchester, Manchester (United Kingdom)

    1993-01-01

    The effects of temperature, precipitation and nutrient perturbations, and their interactions, are being assessed on two contrasting arctic ecosystems to simulate impacts of climate change. One, a high arctic polar semi-desert community, is characterized by a sparse, low and aggregated vegetation cover where plant proliferation is by seedlings, whereas the other, a sub-arctic dwarf shrub health, is characterized by a complete, vegetation cover of erect, clonal dwarf shrubs which spread vegetatively. The developmental processes of seed production were shown to be highly sensitive, even within one growing season to specific environmental perturbations which differed between sites. At the polar semi-desert site, there was a striking effect of the temperature enhancement treatments on phenology and seed-setting of Dryas octopetala ssp. octopetala, with almost no seed-setting occurring in plots experiencing ambient temperatures. By contrast, there were no significant effects of temperature enhancement alone on fruit production of Empetrum hermaphroditum at the sub-Arctic dwarf shrub heath site, although fruit production was significantly influenced by the application of nutrients and/or water. The response of dominant high arctic dwarf shrub to increased temperature suggests that any climate warming may stimulate seed-set. This could be particularly important in the high Arctic where colonization can proceed in areas dominated by bare ground and where genetic recombination may be needed to generate tolerance to predicted changes of great magnitude. In the sub-Arctic, however the closed vegetation is dominated by clonally-proliferating species. Plant fitness will increase here in response to any increased vegetative growth resulting from higher nutrient availability in warmer organic soils. (ua) (59 refs.)

  7. Trichinella in arctic, subarctic and temperate regions

    DEFF Research Database (Denmark)

    Kapel, C. M O

    1997-01-01

    The transmission and occurrence of Trichinella spp according to the zoogeography of different climatic conditions, socioeconomy and human activity are discussed. Comparing arctic, subarctic and temperate regions, it appears that the species of Trichinella present, the composition of the fauna...... and the human activity are all very important interacting factors affecting epidemiology. In Greenland, where only sylvatic trichinellosis is present, the high prevalence in wildlife appears closely connected with polar bear hunting. In the Scandinavian countries, the prevalence of both sylvatic and domestic...

  8. Human paleoecological integration in subarctic eastern Beringia

    Science.gov (United States)

    Lanoë, François B.; Reuther, Joshua D.; Holmes, Charles E.; Hodgins, Gregory W. L.

    2017-11-01

    We contribute to the understanding of megafauna extinction and human dispersal in subarctic eastern Beringia by focusing on changes in the trophic dynamics of the large mammal community as well as the ecological role of humans as a predator and competitor. We reconstruct habitat use by megafauna and humans throughout the Pleistocene-Holocene boundary based on zooarchaeological data and stable isotope ratios of collagen. Our results are consistent with habitat heterogeneity and availability being important factors in the changing abundance of large herbivores. We argue that an increase in herbivore diversity and biomass at the beginning of the Bølling-Allerød interstadial and a relative lack of competitors favored the initial human colonization of subarctic eastern Beringia. As herbivore resources dwindled later in the Late Glacial, people increasingly relied on bison and wapiti. By efficiently extracting some of the highest-ranked resources in the landscape, people are likely to have contributed to the trophic displacement or regional extirpation of other large predators. The ecological patterns that we observe in subarctic eastern Beringia are consistent with a mixture of both top-down and bottom-up controls over biotic turnover.

  9. Patterns of tree species diversity and composition in old-field successional forests in central Illinois

    Science.gov (United States)

    Scott M. Bretthauer; George Z. Gertner; Gary L. Rolfe; Jeffery O. Dawson

    2003-01-01

    Tree species diversity increases and dominance decreases with proximity to forest border in two 60-year-old successional forest stands developed on abandoned agricultural land in Piatt County, Illinois. A regression equation allowed us to quantify an increase in diversity with closeness to forest border for one of the forest stands. Shingle oak is the most dominant...

  10. Assessment of plant species diversity based on hyperspectral indices at a fine scale.

    Science.gov (United States)

    Peng, Yu; Fan, Min; Song, Jingyi; Cui, Tiantian; Li, Rui

    2018-03-19

    Fast and nondestructive approaches of measuring plant species diversity have been a subject of excessive scientific curiosity and disquiet to environmentalists and field ecologists worldwide. In this study, we measured the hyperspectral reflectances and plant species diversity indices at a fine scale (0.8 meter) in central Hunshandak Sandland of Inner Mongolia, China. The first-order derivative value (FD) at each waveband and 37 hyperspectral indices were used to assess plant species diversity. Results demonstrated that the stepwise linear regression of FD can accurately estimate the Simpson (R 2  = 0.83), Pielou (R 2  = 0.87) and Shannon-Wiener index (R 2  = 0.88). Stepwise linear regression of FD (R 2  = 0.81, R 2  = 0.82) and spectral vegetation indices (R 2  = 0.51, R 2  = 0.58) significantly predicted the Margalef and Gleason index. It was proposed that the Simpson, Pielou and Shannon-Wiener indices, which are widely used as plant species diversity indicators, can be precisely estimated through hyperspectral indices at a fine scale. This research promotes the development of methods for assessment of plant diversity using hyperspectral data.

  11. Measures of School Integration: Comparing Coleman's Index to Measures of Species Diversity.

    Science.gov (United States)

    Mercil, Steven Bray; Williams, John Delane

    This study used species diversity indices developed in ecology as a measure of socioethnic diversity, and compared them to Coleman's Index of Segregation. The twelve indices were Simpson's Concentration Index ("ell"), Simpson's Index of Diversity, Hurlbert's Probability of Interspecific Encounter (PIE), Simpson's Probability of…

  12. Body size and measurement of species diversity in large grazing mammals

    NARCIS (Netherlands)

    Oindo, B.O.

    2002-01-01

    Species are by definition different from each other. This fact favours ranking rather than additive indices. However, ecologists have measured species diversity in terms of species richness, or by combining species richness with the relative abundance of species within an area. Both methods raise

  13. Soil, biomass, and management of semi-natural vegetation. II. Factors controlling species diversity

    NARCIS (Netherlands)

    Schaffers, A.P.

    2002-01-01

    Using a wide range of conditions and plant community types, species diversity was investigated in relation to edaphic and non-edaphic site conditions, management, and biomass characteristics. Both standing biomass and aboveground production were investigated, and their effects compared. Three

  14. Butterflies show different functional and species diversity in relationship to vegetation structure and land use

    NARCIS (Netherlands)

    Aguirre-Gutiérrez, J.; WallisDeVries, M.F.; Marshall, L.; van't Zelfde, M.; Villalobos-Arámbula, A.R.; Boekelo, B.; Bartholomeus, H.; Franzén, M.; Biesmeijer, J.C.

    2017-01-01

    Aim: Biodiversity is rapidly disappearing at local and global scales also affecting the functional diversity of ecosystems. We aimed to assess whether functional diversity was correlated with species diversity and whether both were affected by similar land use and vegetation structure drivers.

  15. Individuals and the variation needed for high species diversity in forest trees

    Science.gov (United States)

    James S. Clark

    2010-01-01

    In the past, explanations for high species diversity have been sought at the species level. Theory shows that coexistence requires substantial differences between species, but species-level data rarely provide evidence for such differences. Using data from forests in the southeastern United States, I show here that variation evident at the individual level provides for...

  16. Species diversity and richness of wild birds in Dagona-Waterfowl ...

    African Journals Online (AJOL)

    The study of bird species diversity and richness in Dagona-Waterfowl Sanctuary was carried out during the midst of both early wet and late dry seasons, to provide comprehensive data on wild birds. Dagona Sanctuary is located within the Bade-Nguru Wetland sector. It is one of the important bird areas marked for the ...

  17. Relationship of a lichen species diversity indicator to environmental factors across the coterminous United States

    Science.gov (United States)

    Susan Will-Wolf; Mark J. Ambrose; Randall S. Morin

    2011-01-01

    We have investigated relationships between one simple indicator of lichen species diversity and environmental variables in forests across the coterminous United States. We want to know whether this indicator can help quantify the influence that factors such as climate and air quality have on lichen biodiversity at large scales and whether it will be useful in...

  18. What is the impact of Impatiens glandulifera on species diversity of invaded riparian vegetation?

    Czech Academy of Sciences Publication Activity Database

    Hejda, Martin; Pyšek, Petr

    2006-01-01

    Roč. 132, - (2006), s. 143-152 ISSN 0006-3207 R&D Projects: GA ČR GA206/05/0323 Institutional research plan: CEZ:AV0Z60050516 Keywords : plant invasions * species diversity * dominance Subject RIV: EF - Botanics Impact factor: 2.854, year: 2006

  19. Global latitudinal species diversity gradient in deep-sea benthic foraminifera

    Science.gov (United States)

    Culver, Stephen J.; Buzas, Martin A.

    2000-02-01

    Global scale patterns of species diversity for modern deep-sea benthic foraminifera, an important component of the bathyal and abyssal meiofauna, are examined using comparable data from five studies in the Atlantic, ranging over 138° of latitude from the Norwegian Sea to the Weddell Sea. We show that a pattern of decreasing diversity with increasing latitude characterises both the North and South Atlantic. This pattern is confirmed for the northern hemisphere by independent data from the west-central North Atlantic and the Arctic basin. Species diversity in the North Atlantic northwards from the equator is variable until a sharp fall in the Norwegian Sea (ca. 65°N). In the South Atlantic species diversity drops from a maximum in latitudes less than 30°S and then decreases slightly from 40 to 70°S. For any given latitude, North Atlantic diversity is generally lower than in the South Atlantic. Both ecological and historical factors related to food supply are invoked to explain the formation and maintenance of the latitudinal gradient of deep-sea benthic foraminiferal species diversity. The gradient formed some 36 million years ago when global climatic cooling led to seasonally fluctuating food supply in higher latitudes.

  20. Fire frequency and tree canopy structure influence plant species diversity in a forest-grassland ecotone

    Science.gov (United States)

    David W. Peterson; Peter B. Reich

    2008-01-01

    Disturbances and environmental heterogeneity are two factors thought to influence plant species diversity, but their effects are still poorly understood in many ecosystems. We surveyed understory vegetation and measured tree canopy cover on permanent plots spanning an experimental fire frequency gradient to test fire frequency and tree canopy effects on plant species...

  1. Landscape variation in species diversity and succession as related to topography, soils and human disturbance

    Science.gov (United States)

    Jeffery N. Pearcy; David M. Hix; Stacy A. Drury

    1995-01-01

    Three hundred and thirty-two plots have been sampled on the Wayne National Forest of southeastern Ohio, for the purpose of developing an ecological classification system (ECS). The ECS will be based on the herbaceous and woody vegetation, soils and topography of mature (80-140 year-old), relatively-undisturbed forests. Species diversity changes little across this...

  2. Surficial geology map of the Great Heath, Washington County, Maine

    Science.gov (United States)

    Cameron, Cornelia Clermont; Mullen, Michael K.

    1983-01-01

    The major portion of the Great Heath, comprising 2,645 acres in the Cherryfield quadrangle, Washington County, Maine, generally averaging 13 feet in thickness, but with as great an average as 15 feet, contain an estimated 6,953 ,000 short tons air-dried peat. The peat #s chiefly sphagnum moss with some reed-sedge of high quality according to ASTM standards for agricultural and horticultural use. This same volume of peat may be considered for use as fuel because BTO per pound ranges from 8,600 to 10,500 with low sulfur and high hydrogen contents.

  3. Estimation of carbon flow in a Calluna heath system

    International Nuclear Information System (INIS)

    Roesberg, I.; Oevstedal, D.O.; Seljelid, R.; Schreiner, Oe.; Goksoeyr, J.

    1981-01-01

    In a Culluna heath, plots of 1 m 2 were pulse labelled with 14 CO 2 , and the radioactivity in vegetation above ground, roots, litter and soil organic matter followed for almost two years. In a separate experiment, radioactivity in above ground and root respiration and in soil microbial biomass was determined. A kinetic model for the carbon transfer reaction is presented, and shown to give a satisfactory agreement with the experimental data. The results demonstrate that a major part of the assimilated carbon passes through the roots and into the soil, where it is rapidly mineralized. (author)

  4. High spatial variation in terrestrial arthropod species diversity and composition near the Greenland ice cap

    DEFF Research Database (Denmark)

    Hansen, Rikke Reisner; Hansen, Oskar Liset Pryds; Bowden, Joseph James

    2016-01-01

    Arthropods form a major part of the terrestrial species diversity in the Arctic, and are particularly sensitive to temporal changes in the abiotic environment. It is assumed that most Arctic arthropods are habitat generalists and that their diversity patterns exhibit low spatial variation....... The empirical basis for this assumption, however, is weak. We examine the degree of spatial variation in species diversity and assemblage structure among five habitat types at two sites of similar abiotic conditions and plant species composition in southwest Greenland, using standardized field collection...... methods for spiders, beetles and butterflies. We employed non-metric multidimensional scaling, species richness estimation, community dissimilarity and indicator species analysis to test for local (within site)- and regional (between site)-scale differences in arthropod communities. To identify specific...

  5. REVIEW:Species diversity of indigenous fruits in Indonesia and its potential.

    Directory of Open Access Journals (Sweden)

    TAHAN UJI

    2007-04-01

    Full Text Available Indonesia is rich of species diversity of indigenous fruits. The results of study reported that there are 266 species of indigenous fruits encountered in Indonesia and 62 species of them are cultivated. Four genera of indigenous fruits are recommended to developed in Indonesia, i.e. Durio, Mangifera, Garcinia and Nephelium. This study also reported that duku (Lansium domesticum, salak (Salacca zalacca, buah merah (Pandanus conoideus, and matoa (Pometia pinnata have a good prospect also to be developed in Indonesia.

  6. Tree species diversity mitigates disturbance impacts on the forest carbon cycle.

    Science.gov (United States)

    Silva Pedro, Mariana; Rammer, Werner; Seidl, Rupert

    2015-03-01

    Biodiversity fosters the functioning and stability of forest ecosystems and, consequently, the provision of crucial ecosystem services that support human well-being and quality of life. In particular, it has been suggested that tree species diversity buffers ecosystems against the impacts of disturbances, a relationship known as the "insurance hypothesis". Natural disturbances have increased across Europe in recent decades and climate change is expected to amplify the frequency and severity of disturbance events. In this context, mitigating disturbance impacts and increasing the resilience of forest ecosystems is of growing importance. We have tested how tree species diversity modulates the impact of disturbance on net primary production and the total carbon stored in living biomass for a temperate forest landscape in Central Europe. Using the simulation model iLand to study the effect of different disturbance regimes on landscapes with varying levels of tree species richness, we found that increasing diversity generally reduces the disturbance impact on carbon storage and uptake, but that this effect weakens or even reverses with successional development. Our simulations indicate a clear positive relationship between diversity and resilience, with more diverse systems experiencing lower disturbance-induced variability in their trajectories of ecosystem functioning. We found that positive effects of tree species diversity are mainly driven by an increase in functional diversity and a modulation of traits related to recolonization and resource usage. The results of our study suggest that increasing tree species diversity could mitigate the effects of intensifying disturbance regimes on ecosystem functioning and improve the robustness of forest carbon storage and the role of forests in climate change mitigation.

  7. Links between plant litter chemistry, species diversity, and below-ground ecosystem function

    OpenAIRE

    Meier, Courtney L.; Bowman, William D.

    2008-01-01

    Decomposition is a critical source of plant nutrients, and drives the largest flux of terrestrial C to the atmosphere. Decomposing soil organic matter typically contains litter from multiple plant species, yet we lack a mechanistic understanding of how species diversity influences decomposition processes. Here, we show that soil C and N cycling during decomposition are controlled by the composition and diversity of chemical compounds within plant litter mixtures, rather than by simple metrics...

  8. SPECIES DIVERSITY AND COMMUNITY STRUCTURE OF SUCKING LICE IN YUNNAN, CHINA

    Institute of Scientific and Technical Information of China (English)

    Xian-guoGuo; Ti-junQian; Li-junGuo; JingWang; Wen-geDong; LiZhang; Zhi-minMa; andWeiLi

    2004-01-01

    On the basis of investigating 9 counties (towns) in Yunnan Province of China, the species diversity and community structure of sucking lice on the body surface of small mammal hosts are studied in the paper. Species richness (S) is used to stand for the species diversity. The calculation of community diversity index and evenness are based on Shannon-Wiener's method. 2745 small mammals captured from the investigated sites belong to 10 families, 25 genera and 41 species in 5 orders (Rodentia, Insectivora, Scandentia, Logomorpha and Carnivora) while 18165 individuals of sucking lice collected from the body surface of the small mammal hosts are identified into 4 families, 6 genera and 22 species. The species of sucking lice are much less than the species of their hosts. Most species of small mammals have their fixed sucking lice on their body surface. One species of small mammals usually have few species of sucking lice (1 to 4 species). The close species of the hosts in the taxonomy are found to have the same or similar dominant species of sucking lice on their body surface. The results reveal that the species diversity of sucking lice on small mammals is very low with a very simple community structure. The results also imply there may be a close co-evolution relationship between the lice and the hosts.

  9. Species Diversity of Shallow Water Zoanthids (Cnidaria: Anthozoa: Hexacorallia in Florida

    Directory of Open Access Journals (Sweden)

    James Davis Reimer

    2012-01-01

    Full Text Available Shallow water zooxanthellate zoanthids are a common component of the coral reef ecosystems of the Caribbean. Despite this, their species diversity remains poorly understood. In this study, collected Palythoa, Zoanthus, Isaurus, and Terrazoanthus specimens from the waters of Florida were phylogenetically examined to obtain a better understanding of zoanthid species diversity in the Caribbean. Surprisingly, the results from analyses utilizing three DNA markers (mitochondrial 16S ribosomal DNA, cytochrome oxidase subunit I, and the internal transcribed spacer of ribosomal DNA showed the presence of at least eleven species, of which up to four appear undescribed. Additionally, the presence of the genus Terrazoanthus in the Caribbean was confirmed for the first time. Attempts to match phylogenetic species or clades with original literature were hampered by vague and short original descriptions, and it is clear that for Atlantic Palythoa and Zoanthus species an in-depth and multidisciplinary investigation is needed to reconcile recent phylogenetic results such as in this study with traditional taxonomy. Furthermore, most shallow water zoanthid species from Florida were observed to have close, sister-species relationships with previously investigated species in the Pacific Ocean. These results indicate that many brachycnemic zoanthid species likely had a Caribbean-Pacific distribution until the formation of the Isthmus of Panama. However, due to inadvertent redescriptions, overall species diversity in these two common genera is likely much lower than literature indicates.

  10. Links between plant litter chemistry, species diversity, and below-ground ecosystem function.

    Science.gov (United States)

    Meier, Courtney L; Bowman, William D

    2008-12-16

    Decomposition is a critical source of plant nutrients, and drives the largest flux of terrestrial C to the atmosphere. Decomposing soil organic matter typically contains litter from multiple plant species, yet we lack a mechanistic understanding of how species diversity influences decomposition processes. Here, we show that soil C and N cycling during decomposition are controlled by the composition and diversity of chemical compounds within plant litter mixtures, rather than by simple metrics of plant species diversity. We amended native soils with litter mixtures containing up to 4 alpine plant species, and we used 9 litter chemical traits to evaluate the chemical composition (i.e., the identity and quantity of compounds) and chemical diversity of the litter mixtures. The chemical composition of the litter mixtures was the strongest predictor of soil respiration, net N mineralization, and microbial biomass N. Soil respiration and net N mineralization rates were also significantly correlated with the chemical diversity of the litter mixtures. In contrast, soil C and N cycling rates were poorly correlated with plant species richness, and there was no relationship between species richness and the chemical diversity of the litter mixtures. These results indicate that the composition and diversity of chemical compounds in litter are potentially important functional traits affecting decomposition, and simple metrics like plant species richness may fail to capture variation in these traits. Litter chemical traits therefore provide a mechanistic link between organisms, species diversity, and key components of below-ground ecosystem function.

  11. Robert Heath Lock and his textbook of genetics, 1906.

    Science.gov (United States)

    Edwards, A W F

    2013-07-01

    Robert Heath Lock (1879-1915), a Cambridge botanist associated with William Bateson and R. C. Punnett, published his book Recent Progress in the Study of Variation, Heredity, and Evolution in 1906. This was a remarkable textbook of genetics for one appearing so early in the Mendelian era. It covered not only Mendelism but evolution, natural selection, biometry, mutation, and cytology. It ran to five editions but was, despite its success, largely forgotten following Lock's early death in 1915. Nevertheless it was the book that inspired H. J. Muller to do genetics and was remembered by A. H. Sturtevant as the source of the earliest suggestion that linkage might be related to the exchange of parts between homologous chromosomes. Here we also put forward evidence that it had a major influence on the statistician and geneticist R. A. Fisher at the time he was a mathematics student at Cambridge.

  12. Nitrogen limitation in the coastal heath at Anholt, Denmark

    DEFF Research Database (Denmark)

    Johnsen, Ib; Christensen, Steen; Riis-Nielsen, Torben

    2014-01-01

    ) and phosphorus as KH2PO4 (P-addition) was carried out in the coastal grey dune vegetation of Anholt. The Naddition corresponded to 40 kg N ha−1 year−1 and the Paddition to 7 kg P ha−1 year−1 The experiment included N-, P-, N + P-addition and control. Lichens (genera: mainly Cladonia, Stereocaulon, Cetraria......The purpose of the study was to investigate, whether the coastal grey dune vegetation at Anholt, Denmark, is limited by nitrogen or phosphorus. The island Anholt (22,37 km2) is situated in the centre of Kattegat A two factor fertilization experiment with nitrogen as NH4NO3 (Naddition...... significantly following N and N + P addition. No effect was observed by P addition alone. N limitation of this coastal heath vegetation remote from agricultural and industrial activities was evident. The effect on the plant species of the single application was short-lived. After two-three years of enhanced...

  13. Simulated tri-trophic networks reveal complex relationships between species diversity and interaction diversity.

    Science.gov (United States)

    Pardikes, Nicholas A; Lumpkin, Will; Hurtado, Paul J; Dyer, Lee A

    2018-01-01

    Most of earth's biodiversity is comprised of interactions among species, yet it is unclear what causes variation in interaction diversity across space and time. We define interaction diversity as the richness and relative abundance of interactions linking species together at scales from localized, measurable webs to entire ecosystems. Large-scale patterns suggest that two basic components of interaction diversity differ substantially and predictably between different ecosystems: overall taxonomic diversity and host specificity of consumers. Understanding how these factors influence interaction diversity, and quantifying the causes and effects of variation in interaction diversity are important goals for community ecology. While previous studies have examined the effects of sampling bias and consumer specialization on determining patterns of ecological networks, these studies were restricted to two trophic levels and did not incorporate realistic variation in species diversity and consumer diet breadth. Here, we developed a food web model to generate tri-trophic ecological networks, and evaluated specific hypotheses about how the diversity of trophic interactions and species diversity are related under different scenarios of species richness, taxonomic abundance, and consumer diet breadth. We investigated the accumulation of species and interactions and found that interactions accumulate more quickly; thus, the accumulation of novel interactions may require less sampling effort than sampling species in order to get reliable estimates of either type of diversity. Mean consumer diet breadth influenced the correlation between species and interaction diversity significantly more than variation in both species richness and taxonomic abundance. However, this effect of diet breadth on interaction diversity is conditional on the number of observed interactions included in the models. The results presented here will help develop realistic predictions of the relationships

  14. Conserving the stage: climate change and the geophysical underpinnings of species diversity.

    Directory of Open Access Journals (Sweden)

    Mark G Anderson

    Full Text Available Conservationists have proposed methods for adapting to climate change that assume species distributions are primarily explained by climate variables. The key idea is to use the understanding of species-climate relationships to map corridors and to identify regions of faunal stability or high species turnover. An alternative approach is to adopt an evolutionary timescale and ask ultimately what factors control total diversity, so that over the long run the major drivers of total species richness can be protected. Within a single climatic region, the temperate area encompassing all of the Northeastern U.S. and Maritime Canada, we hypothesized that geologic factors may take precedence over climate in explaining diversity patterns. If geophysical diversity does drive regional diversity, then conserving geophysical settings may offer an approach to conservation that protects diversity under both current and future climates. Here we tested how well geology predicts the species diversity of 14 US states and three Canadian provinces, using a comprehensive new spatial dataset. Results of linear regressions of species diversity on all possible combinations of 23 geophysical and climatic variables indicated that four geophysical factors; the number of geological classes, latitude, elevation range and the amount of calcareous bedrock, predicted species diversity with certainty (adj. R(2 = 0.94. To confirm the species-geology relationships we ran an independent test using 18,700 location points for 885 rare species and found that 40% of the species were restricted to a single geology. Moreover, each geology class supported 5-95 endemic species and chi-square tests confirmed that calcareous bedrock and extreme elevations had significantly more rare species than expected by chance (P<0.0001, strongly corroborating the regression model. Our results suggest that protecting geophysical settings will conserve the stage for current and future biodiversity and may

  15. Comparison of small mammal species diversity near wastewater outfalls, natural streams, and dry canyons

    International Nuclear Information System (INIS)

    Raymer, D.F.; Biggs, J.R.

    1994-03-01

    A wide range of plant and wildlife species utilizes water discharged from facilities at Los Alamos National Laboratory (LANL). The purpose of this study was to compare nocturnal small mammal communities at wet areas created by wastewater outfalls with communities in naturally created wet and dry areas. Thirteen locations within LANL boundaries were selected for small mammal mark-recapture trapping. Three of these locations lacked surface water sources and were classified as open-quotes dry,close quotes while seven sites were associated with wastewater outfalls (open-quotes outfallclose quotes sites), and three were located near natural sources of surface water (open-quotes naturalclose quotes sites). Data was collected on site type (dry, outfall or natural), location, species trapped, and the tag number of each individual captured. This data was used to calculate mean number of species, percent capture rate, and species diversity at each type of site. When data from each type of site was pooled, there were no significant differences in these variables between dry, outfall, and natural types. However, when data from individual sites was compared, tests revealed significant differences. All sites in natural areas were significantly higher than dry areas in daily mean number of species, percent capture rate, and species diversity. Most outfall sites were significantly higher than dry areas in all three variables tested. When volume of water from each outfall site was considered, these data indicated that the number of species, percent capture rate, and species diversity of nocturnal small mammals were directly related to the volume of water at a given outfall

  16. Dams: impacts on the species diversity; Impacts des reservoirs sur la biodiversite

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Domingos de [Quebec Univ., Montreal, PQ (Canada). Dept. de Sciences Biologiques, Inst. de Sciences de l`Environnement

    1996-12-31

    Always you change one ecosystem, you have impacts on the species diversity. The work try to show some impacts of dams for hydroelectric power generation. First of all the author analyses the impacts on the habitats and ecosystems. He considers the problems on a variety of species, since plants and animals that living on the border of the river until the fishes, birds, invertebrates and the mammals. The example of 3 dams, La Grande, Opinaca and Caniapiseau, on Quebec, Canada, are used to give support to the work 14 refs., 1 tab.

  17. About the value of species diversity in arable weeds for weed management

    Directory of Open Access Journals (Sweden)

    Gerowitt, Bärbel

    2016-02-01

    Full Text Available Arable weeds accompany arable land use – we define them based on their affiliation to ar able systems. They are adapted to such a degree that most of them cannot exist without arable land use. Weeds are part of the total biodiversity on arable fields, as primary producers they are basic for important functions within the ecosystem. This paper elaborates the relevance of species diversity in arable weeds for their management. Arable systems can be regarded for the number of different methods for preventive and direct weed control which are realized. Historical arable land use is roughly divided into three periods, which differ concerning the diversity of weed management and the occurring diversity in weed species. Obviously divers weed management in arable systems and diversity in weed species depend on each other, this is illustrated with a simple abstract picture. Arable systems, which are characterised by simpleness, favor the domination of few species which ensure an effective use of the resources within the ecosystem. One consequence under continuous pressure of an overused tool in weed management is that the genetic diversity within a dominating weed population is exploited to ensure this resource use. Current herbicides represent this tool – the results are herbicide resistant biotypes within the weed populations. Species diversity in arable weeds as a rationale within arable production can assist to prevent this development.

  18. Microbial Species Diversity, Community Dynamics, and Metabolite Kinetics of Water Kefir Fermentation

    Science.gov (United States)

    Laureys, David

    2014-01-01

    Water kefir is a sour, alcoholic, and fruity fermented beverage of which the fermentation is started with water kefir grains. These water kefir grains consist of polysaccharide and contain the microorganisms responsible for the water kefir fermentation. In this work, a water kefir fermentation process was followed as a function of time during 192 h to unravel the community dynamics, the species diversity, and the kinetics of substrate consumption and metabolite production. The majority of the water kefir ecosystem was found to be present on the water kefir grains. The most important microbial species present were Lactobacillus casei/paracasei, Lactobacillus harbinensis, Lactobacillus hilgardii, Bifidobacterium psychraerophilum/crudilactis, Saccharomyces cerevisiae, and Dekkera bruxellensis. The microbial species diversities in the water kefir liquor and on the water kefir grains were similar and remained stable during the whole fermentation process. The major substrate, sucrose, was completely converted after 24 h of fermentation, which coincided with the production of the major part of the water kefir grain polysaccharide. The main metabolites of the fermentation were ethanol and lactic acid. Glycerol, acetic acid, and mannitol were produced in low concentrations. The major part of these metabolites was produced during the first 72 h of fermentation, during which the pH decreased from 4.26 to 3.45. The most prevalent volatile aroma compounds were ethyl acetate, isoamyl acetate, ethyl hexanoate, ethyl octanoate, and ethyl decanoate, which might be of significance with respect to the aroma of the end product. PMID:24532061

  19. Species Diversity of Oak Stands and Its Significance for Drought Resistance

    Directory of Open Access Journals (Sweden)

    Jan Kotlarz

    2018-03-01

    Full Text Available Drought periods have an adverse impact on the condition of oak stands. Research on different types of ecosystems has confirmed a correlation between plant species diversity and the adverse effects of droughts. The purpose of this study was to investigate the changes that occurred in an oak stand (Krotoszyn Plateau, Poland under the impact of the summer drought in 2015. We used a method based on remote sensing indices from satellite images in order to detect changes in the vegetation in 2014 and 2015. A positive difference was interpreted as an improvement, whereas a negative one was treated as a deterioration of the stand condition. The Shannon-Wiener species diversity was estimated using an iterative principal component analysis (PCA algorithm based on aerial images. We observed a relationship between the species indices of the individual forest divisions and their response to drought. The highest correlation between the index differences and the Shannon-Wiener indices was found for the Green Normalized Difference Vegetation Index (GNDVI index (+0.74. In addition, correlations were observed between the mean index difference and the percentage shares in the forest divisions of species such as Pinus sylvestris L. (P. sylvestris (+0.67 ± 0.08 and Quercus robur L. (Q. robur (−0.65 ± 0.10. Our results lead us to infer that forest management based on highly diverse habitats is more suitable to meet the challenges in the context of global climatic changes, characterized by increasingly frequent droughts.

  20. Investigating Effects of Participatory Range Management Plans on Species Diversity in Semirum-Isfahan Province

    Directory of Open Access Journals (Sweden)

    M. Borhani

    2016-05-01

    Full Text Available In order to investigate the effects of range management plans on species diversity, richness and evenness in Semirum rangelands, 52 sites (28 with treated plan and 24 without treated plan were selected. The non-parametric indices for species richness (Margalof, Menhinick, Jacknife and counting method and species diversity (Simpson, Camargo, Smith and Wilson and modified Nee were compared in two management plans. The mean comparisons were made by independent T Student Test and Mann-Witheny U Test, and correlation was determined between diversity indices and vegetation parameters. Based on the results there was no significant difference between the two management systems regarding environmental features, while the implementation of range management plans caused significant reduction of stocking rate. Among the studied indices, evenness of species in sites without treated plan was significantly more than the sites with treated plan. The correlation matrix showed that there was a significant positive correlation between species richness and vegetation cover, production of perennial plans, and the rangeland condition and trend, while evenness showed significant negative correlation with these indices. Generally, implementation of range management plans has considerable effect on increasing climax species, dominance of Bromus tomentellus and it causes improvement of rangeland condition and reduction of evenness. This behavior could be explained by the balance between species competition and grazing pressure. Further, succession process of the studied communities demonstrates domination of some desirable species, high production and less diversity.

  1. Importance of riparian remnants for frog species diversity in a highly fragmented rainforest.

    Science.gov (United States)

    Rodríguez-Mendoza, Clara; Pineda, Eduardo

    2010-12-23

    Tropical forests undergo continuous transformation to other land uses, resulting in landscapes typified by forest fragments surrounded by anthropogenic habitats. Small forest fragments, specifically strip-shaped remnants flanking streams (referred to as riparian remnants), can be particularly important for the maintenance and conservation of biodiversity within highly fragmented forests. We compared frog species diversity between riparian remnants, other forest fragments and cattle pastures in a tropical landscape in Los Tuxtlas, Mexico. We found similar species richness in the three habitats studied and a similar assemblage structure between riparian remnants and forest fragments, although species composition differed by 50 per cent. Frog abundance was halved in riparian remnants compared with forest fragments, but was twice that found in pastures. Our results suggest that riparian remnants play an important role in maintaining a portion of frog species diversity in a highly fragmented forest, particularly during environmentally stressful (hot and dry) periods. In this regard, however, the role of riparian remnants is complementary, rather than substitutive, with respect to the function of other forest fragments within the fragmented forest.

  2. Microbial species diversity, community dynamics, and metabolite kinetics of water kefir fermentation.

    Science.gov (United States)

    Laureys, David; De Vuyst, Luc

    2014-04-01

    Water kefir is a sour, alcoholic, and fruity fermented beverage of which the fermentation is started with water kefir grains. These water kefir grains consist of polysaccharide and contain the microorganisms responsible for the water kefir fermentation. In this work, a water kefir fermentation process was followed as a function of time during 192 h to unravel the community dynamics, the species diversity, and the kinetics of substrate consumption and metabolite production. The majority of the water kefir ecosystem was found to be present on the water kefir grains. The most important microbial species present were Lactobacillus casei/paracasei, Lactobacillus harbinensis, Lactobacillus hilgardii, Bifidobacterium psychraerophilum/crudilactis, Saccharomyces cerevisiae, and Dekkera bruxellensis. The microbial species diversities in the water kefir liquor and on the water kefir grains were similar and remained stable during the whole fermentation process. The major substrate, sucrose, was completely converted after 24 h of fermentation, which coincided with the production of the major part of the water kefir grain polysaccharide. The main metabolites of the fermentation were ethanol and lactic acid. Glycerol, acetic acid, and mannitol were produced in low concentrations. The major part of these metabolites was produced during the first 72 h of fermentation, during which the pH decreased from 4.26 to 3.45. The most prevalent volatile aroma compounds were ethyl acetate, isoamyl acetate, ethyl hexanoate, ethyl octanoate, and ethyl decanoate, which might be of significance with respect to the aroma of the end product.

  3. Future stratospheric ozone depletion will affect a subarctic dwarf shrub ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Johanson, Ulf

    1997-02-01

    The stratospheric ozone depletion and the concomitant increase in ultraviolet-B (UV-B, 280-320 nm) radiation is of global concern due to the effects of UV-B on living organisms. To investigate the effects of increased levels of UV-B, a field irradiation system was established at a subarctic dwarf shrub heath in Northern Sweden (68 deg N). An ozone depletion of 15% under clear sky conditions was simulated over a naturally growing ecosystem. The response of both individual components and processes was studied to reveal changes in ecosystem structure and function. Species with different life strategies (evergreen or deciduous) responded differently both in magnitude and direction. The evergreen species were more responsive to UV-B regarding shoot growth, which could be due to cumulative effects in long-lived tissues, since the retardation in relative growth increased over time of exposure. Leaves of evergreen species became thicker under enhanced UV-B, while leaves of deciduous species became thinner. Decomposition studies (laboratory and in situ) showed that indirect effects of UV-B, due to changes in leaf tissue chemistry affected microbial activity and slowed down the decomposition rate. More directly, UV-B decreased the abundance of some fungal species and hence the composition of species. However, no altered decomposition rate was found when decomposition progressed under high UV-B even if the microorganisms were fewer. This could be due to the increased direct photo degradation of litter that compensates for lower microbial activity. The decomposition rate is therefore strongly dependent on the interception of UV-B at the litter layer. This research has shown that ecosystem components and processes are affected in a number of ways and that there are indications of changes in species composition in a long-term perspective due to differences in responsiveness between the different species. 128 refs, 7 figs

  4. Winter Insulation By Snow Accumulation in a Subarctic Treeline Ecosystem Increases Summer Carbon Cycling Rates

    Science.gov (United States)

    Parker, T.; Subke, J. A.; Wookey, P. A.

    2014-12-01

    The effect of snow accumulation on soil carbon and nutrient cycling is attracting substantial attention from researchers. We know that deeper snow accumulation caused by high stature vegetation increases winter microbial activity and therefore carbon and nitrogen flux rates. However, until now the effect of snow accumulation, by buffering winter soil temperature, on subsequent summer soil processes, has scarcely been considered. We carried out an experiment at an alpine treeline in subarctic Sweden in which soil monoliths, contained within PVC collars, were transplanted between forest (deep winter snow) and tundra heath (shallow winter snow). We measured soil CO2efflux over two growing seasons and quantified soil microbial biomass after the second winter. We showed that respiration rates of transplanted forest soil were significantly reduced compared with control collars (remaining in the forest) as a consequence of colder, but more variable, winter temperatures. We hypothesised that microbial biomass would be reduced in transplanted forests soils but found there was no difference compared to control. We therefore further hypothesised that the similarly sized microbial pool in the control is assembled differently to the transplant. We believe that the warmer winters in forests foster more active consortia of decomposer microbes as a result of different abiotic selection pressures. Using an ecosystem scale experimental approach, we have identified a mechanism that influences summer carbon cycling rates based solely on the amount of snow that accumulates the previous winter. We conclude that modification of snow depth as a consequence of changes in vegetation structure is an important mechanism influencing soil C stocks in ecosystems where snow persists for a major fraction of the year.

  5. Sphagnum-dwelling testate amoebae in subarctic bogs are more sensitive to soil warming in the growing season than in winter: the results of eight-year field climate manipulations.

    Science.gov (United States)

    Tsyganov, Andrey N; Aerts, Rien; Nijs, Ivan; Cornelissen, Johannes H C; Beyens, Louis

    2012-05-01

    Sphagnum-dwelling testate amoebae are widely used in paleoclimate reconstructions as a proxy for climate-induced changes in bogs. However, the sensitivity of proxies to seasonal climate components is an important issue when interpreting proxy records. Here, we studied the effects of summer warming, winter snow addition solely and winter snow addition together with spring warming on testate amoeba assemblages after eight years of experimental field climate manipulations. All manipulations were accomplished using open top chambers in a dry blanket bog located in the sub-Arctic (Abisko, Sweden). We estimated sensitivity of abundance, diversity and assemblage structure of living and empty shell assemblages of testate amoebae in the living and decaying layers of Sphagnum. Our results show that, in a sub-arctic climate, testate amoebae are more sensitive to climate changes in the growing season than in winter. Summer warming reduced species richness and shifted assemblage composition towards predominance of xerophilous species for the living and empty shell assemblages in both layers. The higher soil temperatures during the growing season also decreased abundance of empty shells in both layers hinting at a possible increase in their decomposition rates. Thus, although possible effects of climate changes on preservation of empty shells should always be taken into account, species diversity and structure of testate amoeba assemblages in dry subarctic bogs are sensitive proxies for climatic changes during the growing season. Copyright © 2011 Elsevier GmbH. All rights reserved.

  6. Ecosystem respiration depends strongly on photosynthesis in a temperate heath

    DEFF Research Database (Denmark)

    Larsen, Klaus Steenberg; Ibrom, Andreas; Beier, Claus

    2007-01-01

    We measured net ecosystem CO2 flux (F-n) and ecosystem respiration (R-E), and estimated gross ecosystem photosynthesis (P-g) by difference, for two years in a temperate heath ecosystem using a chamber method. The exchange rates of carbon were high and of similar magnitude as for productive forest...... ecosystems with a net ecosystem carbon gain during the second year of 293 +/- 11 g C m(-2) year(-1) showing that the carbon sink strength of heather-dominated ecosystems may be considerable when C. vulgaris is in the building phase of its life cycle. The estimated gross ecosystem photosynthesis and ecosystem.......65) was improved when the P-g rate was incorporated into the model (second year; R-2 = 0.79), suggesting that daytime R-E increased with increasing photosynthesis. Furthermore, the temperature sensitivity of R-E decreased from apparent Q(10) values of 3.3 to 3.9 by the classic equation to a more realistic Q(10...

  7. Bacterial carbon cycling in a subarctic fjord

    DEFF Research Database (Denmark)

    Middelboe, Mathias; Glud, Ronnie Nøhr; Sejr, M.K.

    2012-01-01

    of viruses on bacterial mortality (4–36% of cell production) and carbon cycling. Heterotrophic bacterial consumption was closely coupled with autochthonous BDOC production, and the majority of the primary production was consumed by pelagic bacteria at all seasons. The relatively low measured BGE emphasized......In this seasonal study, we examined the environmental controls and quantitative importance of bacterial carbon consumption in the water column and the sediment in the subarctic Kobbefjord, Greenland. Depth-integrated bacterial production in the photic zone varied from 5.0 ± 2.7 mg C m−2 d−1...... in February to 42 ± 28 mg C m−2 d−1 in May and 34 ± 7 mg C m−2 d−1 in September, corresponding to a bacterial production to primary production ratio of 0.34 ± 0.14, 0.07 ± 0.04, and 0.08 ± 0.06, respectively. Based on measured bacterial growth efficiencies (BGEs) of 0.09–0.10, pelagic bacterial carbon...

  8. Predator-prey interactions as macro-scale drivers of species diversity in mammals

    DEFF Research Database (Denmark)

    Sandom, Christopher James; Sandel, Brody Steven; Dalby, Lars

    Background/Question/Methods Understanding the importance of predator-prey interactions for species diversity is a central theme in ecology, with fundamental consequences for predicting the responses of ecosystems to land use and climate change. We assessed the relative support for different...... mechanistic drivers of mammal species richness at macro-scales for two trophic levels: predators and prey. To disentangle biotic (i.e. functional predator-prey interactions) from abiotic (i.e. environmental) and bottom-up from top-down determinants we considered three hypotheses: 1) environmental factors...... that determine ecosystem productivity drive prey and predator richness (the productivity hypothesis, abiotic, bottom-up), 2) consumer richness is driven by resource diversity (the resource diversity hypothesis, biotic, bottom-up) and 3) consumers drive richness of their prey (the top-down hypothesis, biotic, top...

  9. Species diversity of the Genus Hoya (Asclepiadaceae in Bukit Batikap Sanctuary Forest, Central Kalimantan

    Directory of Open Access Journals (Sweden)

    SRI RAHAYU

    2006-04-01

    Full Text Available The Genus Hoya (Apocynaceae: Asclepiadoideae is being appreciated as exotic ornamental plant in Europe, USA and Australia, while in Indonesia as the country of origin still neglected. Indonesia was predicted have the highest Hoya species diversity (about 60 species from 150 species in the world. Among the major Islands in Indonesia, Kalimantan was predicted have the highest diversity in Hoya species. The inventory of the species has been done in the Bukit Batikap Sanctuary Forest, Muller Mountain in Central Kalimantan. Nine Hoya species of about thirties species in Kalimantan were found in Bukit Batikap, namely: H. coronaria Blume, H. cf. erythrostemma Kerr., H. latifolia G. Don., H. mitrata Kerr., H. nummularioides Const., H. pusilla Rintz, H. revoluta Wight, H. scortechinii King & Gamble, and Hoya cf. vaccinioides Hook.f.

  10. Species diversity, biomass, and carbon stock assessments of a natural mangrove forest in palawan, philippines

    International Nuclear Information System (INIS)

    Abino, A.C.; Lee, Y.J.; Castillo, J.A.A

    2014-01-01

    Philippines claims international recognition for its mangrove-rich ecosystem which play significant functions from the viewpoint of ecosystem services and climate change mitigation. In this study, we assessed the species diversity of the natural mangrove forest of Bahile, Puerto Princesa City, Palawan and evaluated its potential to sequester and store carbon. Sixteen plots with a size of 10 m * 10 m were established using quadrat sampling technique to identify, record, and measure the trees. Diversity index and allometric equations were utilized to determine species diversity, and biomass and carbon stocks. Sediment samples in undisturbed portions using a 30 cm high and 5 cm diameter corer were collected in all plots to determine near-surface sediment carbon. The diversity index (H = 0.9918) was very low having a total of five true mangrove species identified dominated by Rhizophora apiculata Bl. with an importance value index of 148.1%. Among the stands, 74% of the total biomass was attributed to the above-ground (561.2 t ha-1) while 26% was credited to the roots (196.5 t ha-1). The total carbon sequestered and stored in the above-ground and root biomass were 263.8 t C ha-1 (50%) and 92.3 t C ha-1 (17%), respectively. Sediments contained 33% (173.75 t C ha-1) of the mangrove C-stocks. Stored carbon was equivalent to 1944.5 t CO/sub 2/ ha-1. These values suggest that Bahile natural mangrove forest has a potential to sequester and store substantial amounts of atmospheric carbon, hence the need for sustainable management and protection of this important coastal ecosystem. (author)

  11. Tree species diversity promotes aboveground carbon storage through functional diversity and functional dominance.

    Science.gov (United States)

    Mensah, Sylvanus; Veldtman, Ruan; Assogbadjo, Achille E; Glèlè Kakaï, Romain; Seifert, Thomas

    2016-10-01

    The relationship between biodiversity and ecosystem function has increasingly been debated as the cornerstone of the processes behind ecosystem services delivery. Experimental and natural field-based studies have come up with nonconsistent patterns of biodiversity-ecosystem function, supporting either niche complementarity or selection effects hypothesis. Here, we used aboveground carbon (AGC) storage as proxy for ecosystem function in a South African mistbelt forest, and analyzed its relationship with species diversity, through functional diversity and functional dominance. We hypothesized that (1) diversity influences AGC through functional diversity and functional dominance effects; and (2) effects of diversity on AGC would be greater for functional dominance than for functional diversity. Community weight mean (CWM) of functional traits (wood density, specific leaf area, and maximum plant height) were calculated to assess functional dominance (selection effects). As for functional diversity (complementarity effects), multitrait functional diversity indices were computed. The first hypothesis was tested using structural equation modeling. For the second hypothesis, effects of environmental variables such as slope and altitude were tested first, and separate linear mixed-effects models were fitted afterward for functional diversity, functional dominance, and both. Results showed that AGC varied significantly along the slope gradient, with lower values at steeper sites. Species diversity (richness) had positive relationship with AGC, even when slope effects were considered. As predicted, diversity effects on AGC were mediated through functional diversity and functional dominance, suggesting that both the niche complementarity and the selection effects are not exclusively affecting carbon storage. However, the effects were greater for functional diversity than for functional dominance. Furthermore, functional dominance effects were strongly transmitted by CWM of

  12. Remote Sensing of Vegetation Species Diversity: The Utility of Integrated Airborne Hyperspectral and Lidar Data

    Science.gov (United States)

    Krause, Keith Stuart

    The change, reduction, or extinction of species is a major issue currently facing the Earth. Efforts are underway to measure, monitor, and protect habitats that contain high species diversity. Remote sensing technology shows extreme value for monitoring species diversity by mapping ecosystems and using those land cover maps or other derived data as proxies to species number and distribution. The National Ecological Observatory Network (NEON) Airborne Observation Platform (AOP) consists of remote sensing instruments such as an imaging spectrometer, a full-waveform lidar, and a high-resolution color camera. AOP collected data over the Ordway-Swisher Biological Station (OSBS) in May 2014. A majority of the OSBS site is covered by the Sandhill ecosystem, which contains a very high diversity of vegetation species and is a native habitat for several threatened fauna species. The research presented here investigates ways to analyze the AOP data to map ecosystems at the OSBS site. The research attempts to leverage the high spatial resolution data and study the variability of the data within a ground plot scale along with integrating data from the different sensors. Mathematical features are derived from the data and brought into a decision tree classification algorithm (rpart), in order to create an ecosystem map for the site. The hyperspectral and lidar features serve as proxies for chemical, functional, and structural differences in the vegetation types for each of the ecosystems. K-folds cross validation shows a training accuracy of 91%, a validation accuracy of 78%, and a 66% accuracy using independent ground validation. The results presented here represent an important contribution to utilizing integrated hyperspectral and lidar remote sensing data for ecosystem mapping, by relating the spatial variability of the data within a ground plot scale to a collection of vegetation types that make up a given ecosystem.

  13. Patterns of Tree Species Diversity in Relation to Climatic Factors on the Sierra Madre Occidental, Mexico

    Science.gov (United States)

    Silva-Flores, Ramón; Pérez-Verdín, Gustavo; Wehenkel, Christian

    2014-01-01

    Biological diversity can be defined as variability among living organisms from all sources, including terrestrial organisms, marine and other aquatic ecosystems, and the ecological complexes which they are part of. This includes diversity within species, between species, and of ecosystems. Numerous diversity indices combine richness and evenness in a single expression, and several climate-based explanations have been proposed to explain broad-scale diversity patterns. However, climate-based water-energy dynamics appears to be an essential factor that determines patterns of diversity. The Mexican Sierra Madre Occidental occupies an area of about 29 million hectares and is located between the Neotropical and Holarctic ecozones. It shelters a high diversity of flora, including 24 different species of Pinus (ca. 22% on the whole), 54 species of Quercus (ca. 9–14%), 7 species of Arbutus (ca. 50%) and many other trees species. The objectives of this study were to model how tree species diversity is related to climatic and geographic factors and stand density and to test the Metabolic Theory, Productivity-Diversity Hypothesis, Physiological Tolerance Hypothesis, Mid-Domain Effect, and the Water-Energy Dynamic Theory on the Sierra Madre Occidental, Durango. The results supported the Productivity-Diversity Hypothesis, Physiological Tolerance Hypothesis and Water-Energy Dynamic Theory, but not the Mid-Domain Effect or Metabolic Theory. The annual aridity index was the variable most closely related to the diversity indices analyzed. Contemporary climate was found to have moderate to strong effects on the minimum, median and maximum tree species diversity. Because water-energy dynamics provided a satisfactory explanation for the patterns of minimum, median and maximum diversity, an understanding of this factor is critical to future biodiversity research. Quantile regression of the data showed that the three diversity parameters of tree species are generally higher in cold

  14. High plant species diversity indirectly mitigates CO 2- and N-induced effects on grasshopper growth

    Science.gov (United States)

    Strengbom, Joachim; Reich, Peter B.; Ritchie, Mark E.

    2008-09-01

    We examined how elevated atmospheric [CO 2] and higher rate of nitrogen (N) input may influence grasshopper growth by changing food plant quality and how such effects may be modified by species diversity of the plant community. We reared grasshopper nymphs ( Melanoplus femurrubrum) on Poa pratensis from field-grown monocultures or polycultures (16 species) that were subjected to either ambient or elevated levels of CO 2 and N. Grasshopper growth rate was higher on P. pratensis leaves grown in monocultures than in polycultures, higher on P. pratensis grown under elevated than under ambient [CO 2], and higher on P. pratensis grown under elevated than under ambient [N]. The higher growth rate observed on P. pratensis exposed to elevated [CO 2] was, however, less pronounced for polyculture- than monoculture-grown P. pratensis. Growth rate of the grasshoppers was positively correlated with leaf [N], [C], and concentration of soluble carbohydrates + lipids. Concentration of non-structural carbohydrates + lipids was higher in leaves grown under elevated than under ambient [CO 2], and the difference between P. pratensis grown under ambient and elevated [CO 2] was greater for monoculture- than polyculture-grown P. pratensis. In addition, leaf N concentration was higher in P. pratensis grown in monocultures than in polycultures, suggesting that plant species richness, indirectly, may influence insect performance by changed nutritional value of the plants. Because we found interactive effects between all factors included ([CO 2], [N], and plant species diversity), our results suggest that these parameters may influence plant-insect interactions in a complex way that is not predictable from the sum of single factor manipulations.

  15. Patterns of tree species diversity in relation to climatic factors on the Sierra Madre Occidental, Mexico.

    Science.gov (United States)

    Silva-Flores, Ramón; Pérez-Verdín, Gustavo; Wehenkel, Christian

    2014-01-01

    Biological diversity can be defined as variability among living organisms from all sources, including terrestrial organisms, marine and other aquatic ecosystems, and the ecological complexes which they are part of. This includes diversity within species, between species, and of ecosystems. Numerous diversity indices combine richness and evenness in a single expression, and several climate-based explanations have been proposed to explain broad-scale diversity patterns. However, climate-based water-energy dynamics appears to be an essential factor that determines patterns of diversity. The Mexican Sierra Madre Occidental occupies an area of about 29 million hectares and is located between the Neotropical and Holarctic ecozones. It shelters a high diversity of flora, including 24 different species of Pinus (ca. 22% on the whole), 54 species of Quercus (ca. 9-14%), 7 species of Arbutus (ca. 50%) and many other trees species. The objectives of this study were to model how tree species diversity is related to climatic and geographic factors and stand density and to test the Metabolic Theory, Productivity-Diversity Hypothesis, Physiological Tolerance Hypothesis, Mid-Domain Effect, and the Water-Energy Dynamic Theory on the Sierra Madre Occidental, Durango. The results supported the Productivity-Diversity Hypothesis, Physiological Tolerance Hypothesis and Water-Energy Dynamic Theory, but not the Mid-Domain Effect or Metabolic Theory. The annual aridity index was the variable most closely related to the diversity indices analyzed. Contemporary climate was found to have moderate to strong effects on the minimum, median and maximum tree species diversity. Because water-energy dynamics provided a satisfactory explanation for the patterns of minimum, median and maximum diversity, an understanding of this factor is critical to future biodiversity research. Quantile regression of the data showed that the three diversity parameters of tree species are generally higher in cold

  16. Barcoding snakeheads (Teleostei, Channidae) revisited: Discovering greater species diversity and resolving perpetuated taxonomic confusions

    Science.gov (United States)

    Conte-Grand, Cecilia; Britz, Ralf; Dahanukar, Neelesh; Raghavan, Rajeev; Pethiyagoda, Rohan; Tan, Heok Hui; Hadiaty, Renny K.; Yaakob, Norsham S.

    2017-01-01

    Snakehead fishes of the family Channidae are predatory freshwater teleosts from Africa and Asia comprising 38 valid species. Snakeheads are important food fishes (aquaculture, live food trade) and have been introduced widely with several species becoming highly invasive. A channid barcode library was recently assembled by Serrao and co-workers to better detect and identify potential and established invasive snakehead species outside their native range. Comparing our own recent phylogenetic results of this taxonomically confusing group with those previously reported revealed several inconsistencies that prompted us to expand and improve on previous studies. By generating 343 novel snakehead coxI sequences and combining them with an additional 434 coxI sequences from GenBank we highlight several problems with previous efforts towards the assembly of a snakehead reference barcode library. We found that 16.3% of the channid coxI sequences deposited in GenBank are based on misidentifications. With the inclusion of our own data we were, however, able to solve these cases of perpetuated taxonomic confusion. Different species delimitation approaches we employed (BIN, GMYC, and PTP) were congruent in suggesting a potentially much higher species diversity within snakeheads than currently recognized. In total, 90 BINs were recovered and within a total of 15 currently recognized species multiple BINs were identified. This higher species diversity is mostly due to either the incorporation of undescribed, narrow range, endemics from the Eastern Himalaya biodiversity hotspot or the incorporation of several widespread species characterized by deep genetic splits between geographically well-defined lineages. In the latter case, over-lumping in the past has deflated the actual species numbers. Further integrative approaches are clearly needed for providing a better taxonomic understanding of snakehead diversity, new species descriptions and taxonomic revisions of the group. PMID

  17. Patterns of plant species diversity during succession under different disturbance regimes.

    Science.gov (United States)

    Denslow, Julie Sloan

    1980-07-01

    I suggest that between-community variations in diversity patterns during succession in plant communities are due to the effects of selection on life history strategies under different disturbance regimes. Natural disturbances to plant communities are simultaneously a source of mortality for some individuals and a source of establishment sites for others. The plant community consists of a mosaic of disturbance patches (gaps) of different environmental conditions. The composition of the mosaic is described by the size-frequency distribution of the gaps and is dependent on the rates and scales of disturbance. The life-history strategies of plant species dependent on some form of disturbance for establishment of propagules should reflect this size-frequency distribution of disturbance patches. An extension of island biogeographic theory to encompass relative habitat area predicts that a community should be most rich in species adapted to growth and establishment in the spatially most common patch types. Changes in species diversity during succession following large scale disturbance reflect the prevalent life history patterns under historically common disturbance regimes. Communities in which the greatest patch area is in large-scale clearings (e.g. following fire) are most diverse in species establishing seedlings in xeric, high light conditions. Species diversity decreases during succession. Communities in which such large patches are rare are characterized by a large number of species that reach the canopy through small gaps and realtively few which regenerate in the large clearings. Diversity increases during succession following a large scale disturbance.Evidence from communities characterized by different disturbance regimes is summarized from the literature. This hypothesis provides an evolutionary mechanism with which to examine the changes in plant community structure during succession. Diversity peaks occurring at "intermediate levels" of disturbance as

  18. Beyond 16S rRNA Community Profiling: Intra-Species Diversity in the Gut Microbiota

    Science.gov (United States)

    Ellegaard, Kirsten M.; Engel, Philipp

    2016-01-01

    Interactions with microbes affect many aspects of animal biology, including immune system development, nutrition and health. In vertebrates, the gut microbiota is dominated by a small subset of phyla, but the species composition within these phyla is typically not conserved. Moreover, several recent studies have shown that bacterial species in the gut are composed of a multitude of strains, which frequently co-exist in their host, and may be host-specific. However, since the study of intra-species diversity is challenging, particularly in the setting of complex, host-associated microbial communities, our current understanding of the distribution, evolution and functional relevance of intra-species diversity in the gut is scarce. In order to unravel how genomic diversity translates into phenotypic diversity, community analyses going beyond 16S rRNA profiling, in combination with experimental approaches, are needed. Recently, the honeybee has emerged as a promising model for studying gut bacterial communities, particularly in terms of strain-level diversity. Unlike most other invertebrates, the honeybee gut is colonized by a remarkably consistent and specific core microbiota, which is dominated by only eight bacterial species. As for the vertebrate gut microbiota, these species are composed of highly diverse strains suggesting that similar evolutionary forces shape gut community structures in vertebrates and social insects. In this review, we outline current knowledge on the evolution and functional relevance of strain diversity within the gut microbiota, including recent insights gained from mammals and other animals such as the honeybee. We discuss methodological approaches and propose possible future avenues for studying strain diversity in complex bacterial communities. PMID:27708630

  19. Quantifying species diversity with a DNA barcoding-based method: Tibetan moth species (Noctuidae on the Qinghai-Tibetan Plateau.

    Directory of Open Access Journals (Sweden)

    Qian Jin

    Full Text Available With the ongoing loss of biodiversity, there is a great need for fast and effective ways to assess species richness and diversity: DNA barcoding provides a powerful new tool for this. We investigated this approach by focusing on the Tibetan plateau, which is one of the world's top biodiversity hotspots. There have been few studies of its invertebrates, although they constitute the vast majority of the region's diversity. Here we investigated species diversity of the lepidopteran family Noctuidae, across different environmental gradients, using measurements based on traditional morphology as well as on DNA barcoding. The COI barcode showed an average interspecific K2P distance of 9.45±2.08%, which is about four times larger than the mean intraspecific distance (1.85±3.20%. Using six diversity indices, we did not detect any significant differences in estimated species diversity between measurements based on traditional morphology and on DNA barcoding. Furthermore, we found strong positive correlations between them, indicating that barcode-based measures of species diversity can serve as a good surrogate for morphology-based measures in most situations tested. Eastern communities were found to have significantly higher diversity than Western ones. Among 22 environmental factors tested, we found that three (precipitation of driest month, precipitation of driest quarter, and precipitation of coldest quarter were significantly correlated with species diversity. Our results indicate that these factors could be the key ecological factors influencing the species diversity of the lepidopteran family Noctuidae on the Tibetan plateau.

  20. Quantifying Species Diversity with a DNA Barcoding-Based Method: Tibetan Moth Species (Noctuidae) on the Qinghai-Tibetan Plateau

    Science.gov (United States)

    Jin, Qian; Han, Huilin; Hu, XiMin; Li, XinHai; Zhu, ChaoDong; Ho, Simon Y. W.; Ward, Robert D.; Zhang, Ai-bing

    2013-01-01

    With the ongoing loss of biodiversity, there is a great need for fast and effective ways to assess species richness and diversity: DNA barcoding provides a powerful new tool for this. We investigated this approach by focusing on the Tibetan plateau, which is one of the world's top biodiversity hotspots. There have been few studies of its invertebrates, although they constitute the vast majority of the region's diversity. Here we investigated species diversity of the lepidopteran family Noctuidae, across different environmental gradients, using measurements based on traditional morphology as well as on DNA barcoding. The COI barcode showed an average interspecific K2P distance of , which is about four times larger than the mean intraspecific distance (). Using six diversity indices, we did not detect any significant differences in estimated species diversity between measurements based on traditional morphology and on DNA barcoding. Furthermore, we found strong positive correlations between them, indicating that barcode-based measures of species diversity can serve as a good surrogate for morphology-based measures in most situations tested. Eastern communities were found to have significantly higher diversity than Western ones. Among 22 environmental factors tested, we found that three (precipitation of driest month, precipitation of driest quarter, and precipitation of coldest quarter) were significantly correlated with species diversity. Our results indicate that these factors could be the key ecological factors influencing the species diversity of the lepidopteran family Noctuidae on the Tibetan plateau. PMID:23741330

  1. Ecosystem CO2 production during winter in a Swedish subarctic region: the relative importance of climate and vegetation type

    DEFF Research Database (Denmark)

    Grogan, Paul; Jonasson, Sven Evert

    2006-01-01

    General circulation models consistently predict that regional warming will be most rapid in the Arctic, that this warming will be predominantly in the winter season, and that it will often be accompanied by increasing snowfall. Paradoxically, despite the strong cold season emphasis in these predi...... will respond to climate change during winter because they indicate a threshold (~1 m) above which there would be little effect of increased snow accumulation on wintertime biogeochemical cycling....... in these predictions, we know relatively little about the plot and landscape-level controls on tundra biogeochemical cycling in wintertime as compared to summertime. We investigated the relative influence of vegetation type and climate on CO2 production rates and total wintertime CO2 release in the Scandinavian...... subarctic. Ecosystem respiration rates and a wide range of associated environmental and substrate pool size variables were measured in the two most common vegetation types of the region (birch understorey and heath tundra) at four paired sites along a 50 km transect through a strong snow depth gradient...

  2. Local and regional species diversity of benthic Isopoda (Crustacea) in the deep Gulf of Mexico

    Science.gov (United States)

    Wilson, George D. F.

    2008-12-01

    Recent studies of deep-sea faunas considered the influence of mid-domain models in the distribution of species diversity and richness with depth. In this paper, I show that separating local diversity from regional species richness in benthic isopods clarifies mid-domain effects in the distribution of isopods in the Gulf of Mexico. Deviations from the randomised implied species ranges can be informative to understanding general patterns within the Gulf of Mexico. The isopods from the GoMB study contained 135 species, with a total of 156 species including those from an earlier study. More than 60 species may be new to science. Most families of deep-sea isopods (suborder Asellota) were present, although some were extremely rare. The isopod family Desmosomatidae dominated the samples, and one species of Macrostylis (Macrostylidae) was found in many samples. Species richness for samples pooled within sites ranged from 1 to 52 species. Because species in pooled samples were highly correlated with individuals, species diversity was compared across sites using the expected species estimator ( n=15 individuals, ES 15). Six depth transects had idiosyncratic patterns of ES 15, and transects with the greatest short-range variation in topography, such as basins and canyons, had the greatest short-range disparity. Basins on the deep slope did not have a consistent influence (i.e., relatively higher or lower than surrounding areas) on the comparative species diversity. ES 15 of all transects together showed a weak mid-domain effect, peaking around 1200-1500 m, with low values at the shallowest and deepest samples (Sigsbee Abyssal Plain); no longitudinal (east-west) pattern was found. The regional species pool was analyzed by summing the implied ranges of all species. The species ranges in aggregate did not have significant patterns across longitudes, and many species had broad depth ranges, suggesting that the isopod fauna of the Gulf of Mexico is well dispersed. The summed

  3. Anurans in a Subarctic Tundra Landscape Near Cape Churchill, Manitoba

    Science.gov (United States)

    Reiter, M.E.; Boal, C.W.; Andersen, D.E.

    2008-01-01

    Distribution, abundance, and habitat relationships of anurans inhabiting subarctic regions are poorly understood, and anuran monitoring protocols developed for temperate regions may not be applicable across large roadless areas of northern landscapes. In addition, arctic and subarctic regions of North America are predicted to experience changes in climate and, in some areas, are experiencing habitat alteration due to high rates of herbivory by breeding and migrating waterfowl. To better understand subarctic anuran abundance, distribution, and habitat associations, we conducted anuran calling surveys in the Cape Churchill region of Wapusk National Park, Manitoba, Canada, in 2004 and 2005. We conducted surveys along ~l-km transects distributed across three landscape types (coastal tundra, interior sedge meadow-tundra, and boreal forest-tundra interface) to estimate densities and probabilities of detection of Boreal Chorus Frogs (Pseudacris maculata) and Wood Frogs (Lithobates sylvaticus). We detected a Wood Frog or Boreal Chorus Frog on 22 (87%) of 26 transects surveyed, but probability of detection varied between years and species and among landscape types. Estimated densities of both species increased from the coastal zone inland toward the boreal forest edge. Our results suggest anurans occur across all three landscape types in our study area, but that species-specific spatial patterns exist in their abundances. Considerations for both spatial and temporal variation in abundance and detection probability need to be incorporated into surveys and monitoring programs for subarctic anurans.

  4. Selected References on Arctic and Subarctic Prehistory and Ethnology. Revised.

    Science.gov (United States)

    Fitzhugh, William, Comp.; Loring, Stephen, Comp.

    This bibliography provides an introduction to the current literature, in English, on arctic and subarctic prehistory and ethnology. Leads for further research will be found in section 1. Publications listed are not available from the Smithsonian Institution but copies may be found in larger libraries or obtained through inter-library loan.…

  5. Life-Histories of Sub-Arctic Ants

    OpenAIRE

    Heinze, Jürgen

    1993-01-01

    Ant species belonging to seven genera occur in habitats near the tree line in the Northern Hemisphere. An analysis of colony founding strategies suggests that in addition to physiological cold resistance, behavioral and sociometric adaptations might be important for survival and propagation of ants in subarctic biomes.

  6. Tree species diversity in the Eastern Ghats of northern Andhra Pradesh, India

    Directory of Open Access Journals (Sweden)

    M. Tarakeswara Naidu

    2015-06-01

    Full Text Available The present study was conducted to analyze tree species diversity in the tropical forests of the Eastern Ghats of northern Andhra Pradesh, India.  A total of 270 species of trees (≥15cm girth at breast height pertaining to 177 genera belonging to 55 families were recorded.  Among the 270 species, 141 species were observed to be common, 78 were occasional and 51 species were rare in the study area.  Fabaceae was the dominant family with 33 species followed by Rubiaceae with 15 species and Malvaceae, Moraceae and Phyllanthaceae with 13 species each.  The genera with the highest number of species include Ficus (12 species, Diospyros (8 species, Albizia and Grewia (6 species each, Acacia and Bauhinia (5 species each.  Forty-five percent of the species were indigenous. This illustrates the diversity of the tree species in the studied area of the Eastern Ghats and also emphasizes the need for their conservation. 

  7. Multiscale change in reef coral species diversity and composition in the Tropical Eastern Pacific

    Science.gov (United States)

    Gomez, Catalina G.; Gonzalez, Andrew; Guzman, Hector M.

    2018-03-01

    Both natural and anthropogenic factors are changing coral-reef structure and function worldwide. Long-term monitoring has revealed declines in the local composition and species diversity of reefs. Here we report changes in coral-reef community structure over 12 yr (2000-2012) at 17 sites and three spatial scales (reef, gulf and country) in the Tropical Eastern Pacific (Panama). We found a significant 4% annual decline in species population sizes at the country and gulf scales, with significant declines ranging from 3 to 32% at all but one reef. No significant temporal change in expected richness was found at the country scale or in the Gulf of Chiriquí, but a 7% annual decline in expected species richness was found in the Gulf of Panama. There was a 2% increase in community evenness in the Gulf of Chiriquí, but no change in the Gulf of Panama. Significant temporal turnover was found at the country and gulf scales and at 29% of the reefs, a finding mostly explained by changes in species abundance, and losses and gains of rare species. Temporal trends in alpha and beta diversity metrics were explained by water temperature maxima, anomalies and variation that occurred even in the absence of a strong El Niño warming event.

  8. THE POTENTIAL OF VEGETATION SPECIES DIVERSITY FOR ECOTOROURISM DEVELOPMENT AT NATURE RESERVE OF PANJALU LAKE

    Directory of Open Access Journals (Sweden)

    Encep Rahman

    2017-06-01

    Full Text Available The Nature Reserve of Panjalu Lake is one of the oldest conservation area in Indonesia. As a conservation area, Panjalu Lake has different species of flora that are useful as germplasm conservation, science and education. This study aims to know the potential of vegetation species diversity for ecotourism development at Nature Reserve of Panjalu Lake. The inventory method used is line plot sampling with intensity 15 % in two paths of 500 m (adjusted according length of the area and 20 m width. Spacing between lines is 200 m and spacing between observation plot is 100 m. Within each path, 50 m x 20 m observation plots were established. The results showed that there are three species of seedlings with highest IVI, namely: Dysoxylum densiflorum Miq. (47.64 %, Calamus zollingerii (47.64 %, and Sterculia macrophylla Vent. (44.37 %. The four species at sapling stage with highest IVI are: Litsea cassiaefolia (114.29 %; Dysoxylum densiflorum Miq (57.14 %; Litsea sp. and Endiandra rubescens Miq (14.29 %. Three species at pole stage with highest IVI, namely: Dysoxylum densiflorum Miq. (143.04%; Litsea cassiaefolia (99.78 % and Artocarpus elasticus Reinw 9.53 %. Three species at tree stage with highest IVI, namely: Dysoxylum densiflorum Miq (147.924 %, Litsea cassiaefolia (68.753 %, and Eugenia fastigiata Miq ( 31.410 %.

  9. Large herbivores maintain termite-caused differences in herbaceous species diversity patterns.

    Science.gov (United States)

    Okullo, Paul; Moe, Stein R

    2012-09-01

    Termites and large herbivores affect African savanna plant communities. Both functional groups are also important for nutrient redistribution across the landscape. We conducted an experiment to study how termites and large herbivores, alone and in combination, affect herbaceous species diversity patterns in an African savanna. Herbaceous vegetation on large vegetated Macrotermes mounds (with and without large herbivores) and on adjacent savanna areas (with and without large herbivores) was monitored over three years in Lake Mburo National Park, Uganda. We found substantial differences in species richness, alpha diversity, evenness, and stability between termite mound herbaceous vegetation and adjacent savanna vegetation. Within months of fencing, levels of species richness, evenness, and stability were no longer significantly different between savanna and mounds. However, fencing reduced the cumulative number of species, particularly for forbs, of which 48% of the species were lost. Fencing increased the beta diversity (dissimilarity among plots) on the resource-poor (in terms of both nutrients and soil moisture) savanna areas, while it did not significantly affect beta diversity on the resource-rich termite mounds. While termites cause substantial heterogeneity in savanna vegetation, large herbivores further amplify these differences by reducing beta diversity on the savanna areas. Large herbivores are, however, responsible for the maintenance of a large number of forbs at the landscape level. These findings suggest that the mechanisms underlying the effects of termites and large herbivores on savanna plant communities scale up to shape community structure and dynamics at a landscape level.

  10. [Species diversity and temporal niche of entomopathogenic fungi in the extensively managed tea plantation soil].

    Science.gov (United States)

    Guo, Xian-Jian; Shen, Wan-Fang; Liu, Yu-Jun; Chen, Ming-Jun

    2014-11-01

    The species diversity and temporal niche of entomopathogenic fungi community in the rhizosphere soil collected from the extensively managed Huangshan fuzz tip tea plantation were investigated. A total of 140 soil samples were collected at the location of Tangkou Town, Huangshan of Anhui Province during August, 2012 to June, 2013, and totally 1041 fungal isolates were obtained on selective medium with soil dilution plating. The results showed that the entomopathogenic fungi community in the tea plantation soil was diverse with 13 species in 6 genera. Purpureocillium lilacinum (309 strains), Beauveria bassiana (255 strains), and Metarhizium anisopliae (101 strains) were the dominant species accounting for 29.7%, 24.5% and 9.7% of the relative frequency, respectively. P. lilacinum had the widest temporal niche breadth among these dominant entomopathogenic fungi from the tea plantation soil, while B. bassiana had the narrowest. Among the entomopathogenic fungi, B. bassiana and B. brongniartii had the biggest temporal niche overlap of 1.965, while Isaria javanicus and B. bassiana had the smallest of 0.374.

  11. Population cycles and species diversity in dynamic Kill-the-Winner model of microbial ecosystems

    Science.gov (United States)

    Maslov, Sergei; Sneppen, Kim

    2017-01-01

    Determinants of species diversity in microbial ecosystems remain poorly understood. Bacteriophages are believed to increase the diversity by the virtue of Kill-the-Winner infection bias preventing the fastest growing organism from taking over the community. Phage-bacterial ecosystems are traditionally described in terms of the static equilibrium state of Lotka-Volterra equations in which bacterial growth is exactly balanced by losses due to phage predation. Here we consider a more dynamic scenario in which phage infections give rise to abrupt and severe collapses of bacterial populations whenever they become sufficiently large. As a consequence, each bacterial population in our model follows cyclic dynamics of exponential growth interrupted by sudden declines. The total population of all species fluctuates around the carrying capacity of the environment, making these cycles cryptic. While a subset of the slowest growing species in our model is always driven towards extinction, in general the overall ecosystem diversity remains high. The number of surviving species is inversely proportional to the variation in their growth rates but increases with the frequency and severity of phage-induced collapses. Thus counter-intuitively we predict that microbial communities exposed to more violent perturbations should have higher diversity. PMID:28051127

  12. Small mammals as indicators of cryptic plant species diversity in the central Chilean plant endemicity hotspot

    Directory of Open Access Journals (Sweden)

    Meredith Root-Bernstein

    2014-12-01

    Full Text Available Indicator species could help to compensate for a shortfall of knowledge about the diversity and distributions of undersampled and cryptic species. This paper provides background knowledge about the ecological interactions that affect and are affected by herbaceous diversity in central Chile, as part of the indicator species selection process. We focus on the ecosystem engineering role of small mammals, primarily the degu Octodon degus. We also consider the interacting effects of shrubs, trees, avian activity, livestock, slope, and soil quality on herbaceous communities in central Chile. We sampled herbaceous diversity on a private landholding characterized by a mosaic of savanna, grassland and matorral, across a range of degu disturbance intensities. We find that the strongest factors affecting endemic herbaceous diversity are density of degu runways, shrub cover and avian activity. Our results show that the degu, a charismatic and easily identifiable and countable species, could be used as an indicator species to aid potential conservation actions such as private protected area uptake. We map areas in central Chile where degus may indicate endemic plant diversity. This area is larger than expected, and suggests that significant areas of endemic plant communities may still exist, and should be identified and protected. Keywords: Cryptic species, Diversity, Endemic, Indicator species, Octodon degus, Plant

  13. Species diversity of the genus Osmundea (Ceramiales, Rhodophyta) in the Macaronesian region.

    Science.gov (United States)

    Machín-Sánchez, María; Rousseau, Florence; Le Gall, Line; Cassano, Valéria; Neto, Ana I; Sentíes, Abel; T Fujii, Mutue; Gil-Rodríguez, María Candelaria

    2016-08-01

    Species diversity within the genus Osmundea in the Macaronesian region was explored by conducting a comprehensive sampling in the Azores, the Canary, and the Madeira archipelagos. Toward identification, all specimens were first observed alive to verify the absence of corps en cerise, a diagnostic character for the genus and morphometric data were measured (thallus length and width, first-order branches length and width, branchlets length and width, cortical cell length and width in surface view, cortical cell length and width in transverse section). Specimens were sequenced for COI-5P (39 specimens) and three species delimitation methods (Generalized Mixed Yule Coalescent, Automatic Barcode Gap Discovery method, and Poisson Tree Processes) were used to assess the threshold between infra- and interspecific relationships. Subsequently, one or several sequences of plastid-encoded large subunit of RuBisCO (21 specimens) per delimited species were generated to assess the phylogenetic relationships among Macaronesian Osmundea. Moreover, for each delineated species, vegetative and reproductive anatomy was thoroughly documented and, when possible, specimens were either assigned to existing taxa or described as novel species. This integrative approach has provided data for (i) the presence of O. oederi, O. pinnatifida, and O. truncata in Macaronesia; (ii) the proposal of two novel species, O. prudhommevanreinei sp. nov. and O. silvae sp. nov.; and (iii) evidence of an additional species referred as "Osmundea sp.1," which is a sister taxon of O. hybrida. © 2016 Phycological Society of America.

  14. Species Diversity and Botanical Composition of Permanent Grassland as a Response to Different Grazing Management Practices

    Directory of Open Access Journals (Sweden)

    Marie Štýbnarová

    2015-01-01

    Full Text Available The effects of different levels of grazing utilization (two, three and four grazing cycles per year and mineral fertilization (nil-fertilization; N100P30K60 on the botanical composition of permanent grasslands were studied in the locality of Rapotín (Czech Republic, 332 m a.s.l. from 2003–2010. The vegetation of the experimental pasture was classified as Cynosurion. It was found that moderate treatment (three grazing cycles per year without mineral fertilization showed the highest value of diversity index (DI = 6.08, and maximum dominance of legumes (Dmax = 9.1%, particularly Trifolium repens. The highest dominance of grasses (Dmax = 77.7%, mainly Dactylis glomerata and Elytrigia repens, was achieved with the fertilized treatment utilized in two grazing cycles per year. Based on RDA results, tested management treatments explained 26% of species composition variability, where effect of number of grazing cycles per year was five-times higher than effect of fertilization. We recommend grassland utilization in three grazing cycles per year as the most suitable way from the objective of both species diversity and botanical composition of pastures in similar site conditions. Pasture fertilization should be more controlled by careful consideration of individual pasture goals, actual nutrient status of the soil and possible environmental risks.

  15. Study of Tree and Shrub Species Diversity in Forestry Plans with Different Forest Management

    Directory of Open Access Journals (Sweden)

    nooreddin noorian

    2017-12-01

    Full Text Available The aim of this research was to investigate the diversity of tree and shrub species in forestry plan in a watershed and in almost the same ecological conditions but different in forest management plan in the part of Golestan province forest. To this end, the 6675 hectares of the watershed number of 85 in 5 different plans in series one (30-year forestry plan with University Scientific Management, series two Doctor Bahramnia (without implementation and protection, series four Shamoshak, Naharkhoran plan and Sad Abad plan were selected. Inventory grid was designed by a systematic cluster sampling method with 239 circle plots in the study area. In each sample, species composition and diameter at breast height of trees and shrubs were measured. Species diversity in different series, were performed by calculating the heterogeneity indices, species richness and evenness. Statistical analysis of significant differences between the values of biodiversity of woody species among different series was performed by Duncan’s test. The results showed that biodiversity of woody species in the one and two series of Shastkalateh forest under academic management was better than other plans and forestry plan of Naharkhoran is in an unfavorable situation in terms of diversity indices.

  16. Trends in Ostracoda and Cladocera distribution and water chemistry in subarctic Canada: Churchill (Manitoba lakes and ponds revisited

    Directory of Open Access Journals (Sweden)

    Finn A. Viehberg

    2017-03-01

    Full Text Available Ponds and lakes distributed across northern treeline in the Hudson Bay Lowlands near Churchill (Manitoba were revisited to analyse and document the local ecoclimatic and limnological changes that occurred over the period 1997-2012. Our analyses revealed that single events may cause significant changes in salinity, pH and silicate content because of the limited buffer capacity of the inter-connected waters. Planktic freshwater microcrustaceans (Cladocera presented less diverse assemblages and appeared to favour waters that are situated in the boreal forest, while the diversity of benthic species assemblages (Cladocera and Ostracoda was highest in waters located closer to the coastline and in open tundra vegetation. We identified three species that are distinctive for the boreal ecozone (i.e., Candona acuta, Can. acutula and Can. decora and two species (i.e., Tonnacypris glacialis and Can. rawsoni that are elements of (sub-arctic landscapes and potentially endangered as the northern treeline expands due to rapid warming. These species are thought to be useful indicators for future ecosystem quality assessments and/or ecosystem service management programs. Our findings were compared to other studies completed in the boreal Yukon Territory and revealed that species diversity is closely linked to landscape history.

  17. Lack of congruence in species diversity indices and community structures of planktonic groups based on local environmental factors.

    Science.gov (United States)

    Doi, Hideyuki; Chang, Kwang-Hyeon; Nishibe, Yuichiro; Imai, Hiroyuki; Nakano, Shin-ichi

    2013-01-01

    The importance of analyzing the determinants of biodiversity and community composition by using multiple trophic levels is well recognized; however, relevant data are lacking. In the present study, we investigated variations in species diversity indices and community structures of the plankton taxonomic groups-zooplankton, rotifers, ciliates, and phytoplankton-under a range of local environmental factors in pond ecosystems. For each planktonic group, we estimated the species diversity index by using linear models and analyzed the community structure by using canonical correspondence analysis. We showed that the species diversity indices and community structures varied among the planktonic groups and according to local environmental factors. The observed lack of congruence among the planktonic groups may have been caused by niche competition between groups with similar trophic guilds or by weak trophic interactions. Our findings highlight the difficulty of predicting total biodiversity within a system, based upon a single taxonomic group. Thus, to conserve the biodiversity of an ecosystem, it is crucial to consider variations in species diversity indices and community structures of different taxonomic groups, under a range of local conditions.

  18. Litter quality effects of beech and hornbeam on undergrowth species diversity in Luxembourg forests on limestone and decalcified marl

    NARCIS (Netherlands)

    Kooijman, A.M.

    2010-01-01

    Question: Do beech and hornbeam differ in undergrowth species diversity, and could these differences be explained by mass of the organic layer, pH or soil moisture? Could species richness under beech and hornbeam be explained by differences in N dynamics? Location: Ancient forests dominated by beech

  19. Contrasting distributions of dissolved gaseous mercury concentration and evasion in the North Pacific Subarctic Gyre and the Subarctic Front

    Science.gov (United States)

    Kim, Hyunji; Rhee, Tae Siek; Hahm, Doshik; Hwang, Chung Yeon; Yang, Jisook; Han, Seunghee

    2016-04-01

    The distribution of dissolved gaseous mercury (DGM) and the oxidation-reduction processes of mercury (Hg) in the surface and subsurface ocean are currently understudied despite their importance in ocean-atmosphere interactions. We investigated the Hg(0) evasion and the DGM distribution at water depths of 2-500 m in the Subarctic Front, Western Subarctic Gyre, and Bering Sea of the Northwestern Pacific. The mean DGM concentration in the surface mixed water (evasion flux were significantly higher in the Subarctic Front (125±5.0 fM and 15 pmol m-2 h-1, respectively), which typically has lower nutrient levels and higher primary production, than in the Western Subarctic Gyre and the Bering Sea (74±18 fM and 3.2±1.2 pmol m-2 h-1, respectively). The variation in the chlorophyll-a concentration and extracellular protease activity predicted 54% and 48% of the DGM variation, respectively, in the euphotic zone (2-50 m). The DGM concentration in aphotic intermediate water (415±286 fM) was positively correlated to the apparent oxygen utilization (AOU; r2=0.94 and pevasion is closely linked to primary production in euphotic water and organic remineralization in aphotic intermediate water. The oceanic alterations in these factors may induce significant modification in Hg redox speciation in the Northwestern Pacific.

  20. Ecosystem partitioning of 15N-glycine after long-term climate and nutrient manipulations, plant clipping and addition of labile carbon in a subarctic heath tundra

    DEFF Research Database (Denmark)

    Sørensen, Pernille Lærkedal; Michelsen, Anders; Jonasson, Sven Evert

    2008-01-01

    of nitrogen (N). Here, we studied 15N label incorporation into microbes, plants and soil N pools after both long-term (12 years) climate manipulation and nutrient addition, plant clipping and a pulse-addition of labile C to the soil, in order to gain information on interactions among soil N and C pools...... addition. However, plants exerted control on the soil inorganic N concentrations and recovery of total dissolved 15N (TD15N), and likewise the microbes reduced these soil pools, but only when fed with labile C. Soil microbes in clipped plots were primarily C limited, and the findings of reduced N...... availability, both in the presence of plants and with the combined treatment of plant clipping and addition of sugar, suggest that the plant control of soil N pools was not solely due to plant uptake of soil N, but also partially caused by plants feeding labile C to the soil microbes, which enhanced...

  1. The relationship between species diversity and genetic structure in the rare Picea chihuahuana tree species community, Mexico.

    Science.gov (United States)

    Simental-Rodríguez, Sergio Leonel; Quiñones-Pérez, Carmen Zulema; Moya, Daniel; Hernández-Tecles, Enrique; López-Sánchez, Carlos Antonio; Wehenkel, Christian

    2014-01-01

    Species diversity and genetic diversity, the most basic elements of biodiversity, have long been treated as separate topics, although populations evolve within a community context. Recent studies on community genetics and ecology have suggested that genetic diversity is not completely independent of species diversity. The Mexican Picea chihuahuana Martínez is an endemic species listed as "Endangered" on the Red List. Forty populations of Chihuahua spruce have been identified. This species is often associated with tree species of eight genera in gallery forests. This rare Picea chihuahuana tree community covers an area no more than 300 ha and has been subject of several studies involving different topics such as ecology, genetic structure and climate change. The overall aim of these studies was to obtain a dataset for developing management tools to help decision makers implement preservation and conservation strategies. However, this unique forest tree community may also represent an excellent subject for helping us to understand the interplay between ecological and evolutionary processes in determining community structure and dynamics. The AFLP technique and species composition data were used together to test the hypothesis that species diversity is related to the adaptive genetic structure of some dominant tree species (Picea chihuahuana, Pinus strobiformis, Pseudotsuga menziesii and Populus tremuloides) of the Picea chihuahuana tree community at fourteen locations. The Hill numbers were used as a diversity measure. The results revealed a significant correlation between tree species diversity and genetic structure in Populus tremuloides. Because the relationship between the two levels of diversity was found to be positive for the putative adaptive AFLP detected, genetic and species structures of the tree community were possibly simultaneously adapted to a combination of ecological or environmental factors. The present findings indicate that interactions between

  2. Species diversity of plant communities from territories with natural origin radionuclides contamination

    Energy Technology Data Exchange (ETDEWEB)

    Kaneva, A.V.; Belykh, E.S.; Maystrenko, T.A.; Grusdev, B.I.; Zainullin, V.G.; Vakhrusheva, O.M. [Institute of Biology, Komi Scientific Center, Ural Division of RAS, Syktyvkar, 167982 (Russian Federation); Oughton, D. [Norwegian University of Life Sciences, P.O. Box 5003, NO-1432 Aas (Norway)

    2014-07-01

    Since plants dominate every landscape, the impact of any environmental stressor on plants can directly affect the structure and function of an ecosystem, resulting in decreased primary productivity and degradation of wildlife habitat. The investigation goal of the present research was to study how vascular plant species' composition at a former radium mining site could be related to i) soil contamination with heavy metals and uranium and thorium decay chain radionuclides and ii) soil agrochemical properties. Between the 1930's and 1950's, the commercial extraction of radium, storage of the uranium mill tailings and radium production wastes, together with deactivation of the site with a mixture of sand and gravel completely destroyed plant communities in the vicinity of Vodny settlement (Komi Republic, Russia). The plant cover recovery started more than 60 years ago, and resulted in overgrowing with common grassland plant species. Three meadow sites were investigated, one with low contamination (on the territory of former radium production plant), one with high contamination (waste storage cell) and a reference sites out of the radiochemical plant zone of influence, but with similar natural conditions. Geo-botanical descriptions revealed 134 vascular plant species from 34 families in the meadow communities studied. The greatest richness was seen for Poaceae, Asteraceae, Rosaceae and Fabaceae families; others had 1-5 species. The highest richness in diversity was seen at reference sites with 95 vascular plant species. 87 species were registered on low contaminated sites and 75 species on high contaminated. Perennial herbs were the dominant life form on all the studied meadow communities. Arboreal species expansion in vegetation was noted at both experimental and reference sites. Shannon index calculations indicated a significant (p<0.05) decrease in species diversity on sample areas of the highly contaminated radioactive waste storage cell. Mean values

  3. Species diversity of phytoseiid mites on different ecosystems in Sari district

    Directory of Open Access Journals (Sweden)

    Javad Omidi

    2016-03-01

    Full Text Available Introduction Mites of the Phytoseiidae family have been extensively studied as biological control agents of different mites and insect pests. Some species also feed on nematodes, fungal spores, pollen and exudates from plants and insects. About 2,300 phytoseiid species belonging to 90 genera have been described in this family (Chant and McMurtry 2007. Considerable efforts have been made in recent years to the collection and identification of the predaceous phytoseiid mites in Iran (Rahmani et al. 2010. Despite some studies on phytoseiid mites in Iran, our knowledge remains limited about their fauna and diversity in Mazandaran province. The data of these studies showed that until recently, only 75 species were reported from Iran. The objective of this study was to evaluate the species diversity of Phytoseiidae and access to effective predatory mites for biological control of injurious mite pests in Sari, the center of Mazandaran province (Southern coast of the Caspian Sea, 35 ° 47'-36 ° 35' N, 50 ° 34'-54 ° 10' E Materials and methods Samples were taken from 80 plant species belonging to 46 plant families including forest trees, orchards and farm crops representing three types of ecosystems from September 2011 to October 2012. Harvested samples of each plant were separately collected in plastic bags and labeled with region and date of collection. The bags were transported to the laboratory on the same day and stored in a refrigerator at about 4°C for up to a week, until the materials washed for mite extraction. Samples were composed of leaves, stems and shoots of different ages and the number of leaves per sample varied between plant species. In order to assimilate the samples, a volume nearly equal mass of each sample were put in a two-liter water container. The mites were floated on water by adding 1.5 liters of tap water and a few droplets of detergent. The plant leaves and shoots were shaken for several times until the mites fall from

  4. Multiscale mapping of species diversity under changed land use using imaging spectroscopy.

    Science.gov (United States)

    Paz-Kagan, Tarin; Caras, Tamir; Herrmann, Ittai; Shachak, Moshe; Karnieli, Arnon

    2017-07-01

    Land use changes are one of the most important factors causing environmental transformations and species diversity alterations. The aim of the current study was to develop a geoinformatics-based framework to quantify alpha and beta diversity indices in two sites in Israel with different land uses, i.e., an agricultural system of fruit orchards, an afforestation system of planted groves, and an unmanaged system of groves. The framework comprises four scaling steps: (1) classification of a tree species distribution (SD) map using imaging spectroscopy (IS) at a pixel size of 1 m; (2) estimation of local species richness by calculating the alpha diversity index for 30-m grid cells; (3) calculation of beta diversity for different land use categories and sub-categories at different sizes; and (4) calculation of the beta diversity difference between the two sites. The SD was classified based on a hyperspectral image with 448 bands within the 380-2500 nm spectral range and a spatial resolution of 1 m. Twenty-three tree species were classified with high overall accuracy values of 82.57% and 86.93% for the two sites. Significantly high values of the alpha index characterize the unmanaged land use, and the lowest values were calculated for the agricultural land use. In addition, high values of alpha indices were found at the borders between the polygons related to the "edge-effect" phenomenon, whereas low alpha indices were found in areas with high invasion species rates. The beta index value, calculated for 58 polygons, was significantly lower in the agricultural land use. The suggested framework of this study succeeded in quantifying land use effects on tree species distribution, evenness, and richness. IS and spatial statistics techniques offer an opportunity to study woody plant species variation with a multiscale approach that is useful for managing land use, especially under increasing environmental changes. © 2017 by the Ecological Society of America.

  5. Effect of Cutting Pattern and Fertilization Level on Species Diversity and Evaluation of Grassland Quality

    Directory of Open Access Journals (Sweden)

    Josef Raus

    2014-01-01

    Full Text Available The effects of fertilization level and cutting pattern on the species diversity and quality of a meadow stand were assessed in 2004–2012 in the small plot trial established in 2003 in Vatín, Vysočina Region, Czech Republic. Four levels of fertilization (none; N0 + P30 + K60 kg∙ha−1; N90 + P30 + K60 kg∙ha−1; N180 + P30 + K60 kg∙ha−1 were combined with four treatments of exploitation intensity (4 cuts per year, first cut on 15th May, every next after 45 days; 3 cuts per year, first cut on 30th May, every next after 60 days; 2 cuts per year, first cut on 15th June, next after 90 days; 2 cuts per year, first cut on 30th June, next after 90 days. Numbers of species, Simpson’s diversity index and evaluation of grassland quality according to Novák (2004 were evaluated. Numbers of species and Simpson’s diversity index were significantly affected by both fertilization level and cutting pattern. Species richness decreased along with increasing fertilization rates from 29.4 (no fertilization to 27.8 (N180PK. When comparing cutting pattern treatments the highest species richness was found in four-cut swards (29.6 in average of fertilization levels and it declines towards late double-cut regime (27.2. The Simpson’s index generally increased from two-cut swards to four-cut and from fertilized treatments to control. Grassland quality was significantly affected by cutting pattern. Values increased from four-cut swards (38.1 to two-cut ones (43.8 and 44.0 in early and late harvest respectively.

  6. Reassessment of Species Diversity of the Subfamily Denticollinae (Coleoptera: Elateridae through DNA Barcoding.

    Directory of Open Access Journals (Sweden)

    Taeman Han

    Full Text Available The subfamily Denticollinae is a taxonomically diverse group in the family Elateridae. Denticollinae includes many morphologically similar species and crop pests, as well as many undescribed species at each local fauna. To construct a rapid and reliable identification system for this subfamily, the effectiveness of molecular species identification was assessed based on 421 cytochrome c oxidase subunit I (COI sequences of 84 morphologically identified species. Among the 84 morphospecies, molecular species identification of 60 species (71.4% was consistent with their morphological identifications. Six cryptic and/or pseudocryptic species with large genetic divergence (>5% were confirmed by their sympatric or allopatric distributions. However, 18 species, including a subspecies, had ambiguous genetic distances and shared overlapping intra- and interspecific genetic distances (range: 2.12%-3.67% suggesting incomplete lineage sorting, introgression of mitochondrial genome, or affection by endosymbionts, such as Wolbachia infection, between species and simple genetic variation within species. In this study, we propose a conservative threshold of 3.6% for convenient molecular operational taxonomic unit (MOTU identification in the subfamily Denticollinae based on the results of pairwise genetic distances analyses using neighbor-joining, mothur, Automatic Barcode Gap Discovery analysis, and tree-based species delimitation by Poisson Tree Processes analysis. Using the 3.6% threshold, we identified 87 MOTUs and found 8 MOTUs in the interval between 2.5% to 3.5%. Evaluation of MOTUs identified in this range requires integrative species delimitation, including review of morphological and ecological differences as well as sensitive genetic markers. From this study, we confirmed that COI sequence is useful for reassessing species diversity for polymorphic and polytypic species occurring in sympatric and allopatric distributions, and for a single species having

  7. Investigation of weed species diversity and community structure in saffron fields of Khorasan

    Directory of Open Access Journals (Sweden)

    Surur Khorramdel

    2017-09-01

    Full Text Available Weedy flora of agroecosystems is composed of many species that have evolved in response to cropping system practices by occupying the niches left available in agroecosystems. In order to study weed species diversity and community structure in the saffron fields of Khorasan province, a survey trial was carried out in seven counties (including Mashhad, Neyshabur, Birjandn, Ghaen, Gonabad, Torbat-e Jam and Torbat-e Heydari during 2014 and 2015 from vegetative growth, dormant to flowering stages of saffron randomly dropped 1×1 m2 quadrates in 50 fields based on a systematic method as W pattern. The counties were clustered by the hierarchical complete linkage method based on Euclidean. Biodiversity indices such as stability coefficient, Simpson, Shannon–Wiener, Margalef and Menhinick were computed. The results indicated that the dominant weeds in saffron fields belong to 19 families and 50 species. Poaceae, Brassicaceae, Asteraceae and Fabaceae were dominant families with 11, 9, 8 and 6 species, respectively. The majority of weed species were dicotyledonous, C3, noxious and annual plants. The highest stability coefficients in the stages of growth of saffron were calculated in Alhagi camelorum, Avena fatua and Achillea millefolium to be 30.81, 24.11 and 12.14, respectively. All weed species except for Alhagi camelorum (sustainable species and Avena fatua (temporary species were recognized as causal species. The maximum diversity indices for weed species were recorded at the vegetative phase of saffron. Correlation coefficient between weed density and yield loss of saffron was computed as R2=0.98. Based on diversity indices for weed species, different counties were clustered in three groups at 75% similarity level.

  8. Are Tree Species Diversity and Genotypic Diversity Effects on Insect Herbivores Mediated by Ants?

    Directory of Open Access Journals (Sweden)

    María José Campos-Navarrete

    Full Text Available Plant diversity can influence predators and omnivores and such effects may in turn influence herbivores and plants. However, evidence for these ecological feedbacks is rare. We evaluated if the effects of tree species (SD and genotypic diversity (GD on the abundance of different guilds of insect herbivores associated with big-leaf mahogany (Swietenia macrophylla were contingent upon the protective effects of ants tending extra-floral nectaries of this species. This study was conducted within a larger experiment consisting of mahogany monocultures and species polycultures of four species and -within each of these two plot types- mahogany was represented by either one or four maternal families. We selected 24 plots spanning these treatment combinations, 10 mahogany plants/plot, and within each plot experimentally reduced ant abundance on half of the selected plants, and surveyed ant and herbivore abundance. There were positive effects of SD on generalist leaf-chewers and sap-feeders, but for the latter group this effect depended on the ant reduction treatment: SD positively influenced sap-feeders under ambient ant abundance but had no effect when ant abundance was reduced; at the same time, ants had negative effects on sap feeders in monoculture but no effect in polyculture. In contrast, SD did not influence specialist stem-borers or leaf-miners and this effect was not contingent upon ant reduction. Finally, GD did not influence any of the herbivore guilds studied, and such effects did not depend on the ant treatment. Overall, we show that tree species diversity influenced interactions between a focal plant species (mahogany and ants, and that such effects in turn mediated plant diversity effects on some (sap-feeders but not all the herbivores guilds studied. Our results suggest that the observed patterns are dependent on the combined effects of herbivore identity, diet breadth, and the source of plant diversity.

  9. The impact of enhanced ultraviolet-B radiation on litter quality and decomposition processes in Vaccinium leaves from the Subarctic

    Energy Technology Data Exchange (ETDEWEB)

    Gehrke, C.; Johanson, U. [Lund Univ. (Sweden); Callaghan, T. V.; Chadwick, D.; Robinson, C. H.

    1995-03-15

    The aim of this study was to investigate how UV-B radiation will affect 1) the quality of plant litter grown under different UV-B levels in the Subarctic and 2) decomposition under different UV-B levels. The deciduous dwarf shrubs Vaccinium uliginosum and V. myrtillus grew under ambient and enhanced UV-B (corresponding to 15% ozone depletion) in a natural heath ecosystem in the Subarctic. After two growing seasons senesced leaves were collected and decomposed in a 2 × 2 factorial experiment under both laboratory conditions for 62 d (V. uliginosum: no UV-B and 10 kJ m{sup -2} d{sup -1} UV- B{sub BE}) and under field conditions for twelve months (V. myrtillus: ambient and enhanced UV-B corresponding 15% ozone depletion). Additionally, colonization and growth of decomposing fungi were studied on leaves decomposed without and with UV-B in the laboratory. The enhanced UV-B during growth changed the litter quality (decrease in α-cellulose, increase in tannins). Subsequently the microbial respiration was decreased. This and the decreased cellulose/lignin ratio may have led to the lower relative mass loss due to treatments as detected both after 62 d decomposition in the laboratory and after twelve months decomposition in the field. The UV-B during decomposition decreased the proportion of lignin in the plant residues, which is possibly due to photodegradation by UV-B. Total microbial respiration decreased, indicating the decomposers' sensitivity to UV-B. In general, the litter decomposing under UV-B was less colonized by fungal decomposers. Mucor hiemalis and Truncatella truncata were significantly more abundant in the control, indicating sensitivity to UV-B radiation, while Penicillium brevicompactum was equally abundant in the UV-B and control. There is strong indication of a change in decomposer fungal community structure due to UV-B. Just one of the three fungal species common on the control litter was dominant on leaves decomposed under UV-B. (author)

  10. The impact of enhanced ultraviolet-B radiation on litter quality and decomposition processes in Vaccinium leaves from the Subarctic

    International Nuclear Information System (INIS)

    Gehrke, C.; Johanson, U.; Callaghan, T.V.; Chadwick, D.; Robinson, C.H.

    1995-01-01

    The aim of this study was to investigate how UV-B radiation will affect 1) the quality of plant litter grown under different UV-B levels in the Subarctic and 2) decomposition under different UV-B levels. The deciduous dwarf shrubs Vaccinium uliginosum and V. myrtillus grew under ambient and enhanced UV-B (corresponding to 15% ozone depletion) in a natural heath ecosystem in the Subarctic. After two growing seasons senesced leaves were collected and decomposed in a 2 × 2 factorial experiment under both laboratory conditions for 62 d (V. uliginosum: no UV-B and 10 kJ m -2 d -1 UV- B BE ) and under field conditions for twelve months (V. myrtillus: ambient and enhanced UV-B corresponding 15% ozone depletion). Additionally, colonization and growth of decomposing fungi were studied on leaves decomposed without and with UV-B in the laboratory. The enhanced UV-B during growth changed the litter quality (decrease in α-cellulose, increase in tannins). Subsequently the microbial respiration was decreased. This and the decreased cellulose/lignin ratio may have led to the lower relative mass loss due to treatments as detected both after 62 d decomposition in the laboratory and after twelve months decomposition in the field. The UV-B during decomposition decreased the proportion of lignin in the plant residues, which is possibly due to photodegradation by UV-B. Total microbial respiration decreased, indicating the decomposers' sensitivity to UV-B. In general, the litter decomposing under UV-B was less colonized by fungal decomposers. Mucor hiemalis and Truncatella truncata were significantly more abundant in the control, indicating sensitivity to UV-B radiation, while Penicillium brevicompactum was equally abundant in the UV-B and control. There is strong indication of a change in decomposer fungal community structure due to UV-B. Just one of the three fungal species common on the control litter was dominant on leaves decomposed under UV-B. (author)

  11. Quantifying landscape-level methane fluxes in subarctic Finland using a multiscale approach.

    Science.gov (United States)

    Hartley, Iain P; Hill, Timothy C; Wade, Thomas J; Clement, Robert J; Moncrieff, John B; Prieto-Blanco, Ana; Disney, Mathias I; Huntley, Brian; Williams, Mathew; Howden, Nicholas J K; Wookey, Philip A; Baxter, Robert

    2015-10-01

    Quantifying landscape-scale methane (CH4 ) fluxes from boreal and arctic regions, and determining how they are controlled, is critical for predicting the magnitude of any CH4 emission feedback to climate change. Furthermore, there remains uncertainty regarding the relative importance of small areas of strong methanogenic activity, vs. larger areas with net CH4 uptake, in controlling landscape-level fluxes. We measured CH4 fluxes from multiple microtopographical subunits (sedge-dominated lawns, interhummocks and hummocks) within an aapa mire in subarctic Finland, as well as in drier ecosystems present in the wider landscape, lichen heath and mountain birch forest. An intercomparison was carried out between fluxes measured using static chambers, up-scaled using a high-resolution landcover map derived from aerial photography and eddy covariance. Strong agreement was observed between the two methodologies, with emission rates greatest in lawns. CH4 fluxes from lawns were strongly related to seasonal fluctuations in temperature, but their floating nature meant that water-table depth was not a key factor in controlling CH4 release. In contrast, chamber measurements identified net CH4 uptake in birch forest soils. An intercomparison between the aerial photography and satellite remote sensing demonstrated that quantifying the distribution of the key CH4 emitting and consuming plant communities was possible from satellite, allowing fluxes to be scaled up to a 100 km(2) area. For the full growing season (May to October), ~ 1.1-1.4 g CH4  m(-2) was released across the 100 km(2) area. This was based on up-scaled lawn emissions of 1.2-1.5 g CH4  m(-2) , vs. an up-scaled uptake of 0.07-0.15 g CH4  m(-2) by the wider landscape. Given the strong temperature sensitivity of the dominant lawn fluxes, and the fact that lawns are unlikely to dry out, climate warming may substantially increase CH4 emissions in northern Finland, and in aapa mire regions in general. © 2015 The

  12. Species Diversity Effects on Productivity, Persistence and Quality of Multispecies Swards in a Four-Year Experiment

    DEFF Research Database (Denmark)

    Jing, Jingying; Søegaard, Karen; Cong, Wen-Feng

    2017-01-01

    ), neutral detergent fiber (NDF) and crude protein (CP), and a lower concentration of ash than the 10-mix and 12-mix. Slurry application increased annual yield production by 10% and changed the botanical composition, increasing the proportion of grass and decreasing the proportion of legumes. Compared......Plant species diversity may benefit natural grassland productivity, but its effect in managed grassland systems is not well understood. A four-year multispecies grassland experiment was conducted to investigate the effect of species diversity±legumes and non-leguminous forbs±on productivity...... increased sward production and yield persistence under cutting regime. The 12-mix had the highest yield from the second year onwards and no statistically significant yield reduction over four years, while annual yields in the 3-mix and 10-mix decreased significantly with increasing grassland age. The higher...

  13. The impact of ancestral heath management on soils and landscapes. A reconstruction based on paleoecological analyses of soil records in the middle and southeast Netherlands.

    Science.gov (United States)

    van Mourik, Jan; Doorenbosch, Marieke

    2016-04-01

    The evolution of heath lands during the Holocene has been registered in various soil records . Paleoecological analyses of these records enable to reconstruct the changing economic and cultural management of heaths and the consequences for landscape and soils. Heaths are characteristic components of cultural landscape mosaics on sandy soils in the Netherlands. The natural habitat of heather species was moorland. At first, natural events like forest fires and storms caused small-scale forest degradation, in addition on the forest degradation accelerated due to cultural activities like forest grazing, wood cutting and shifting cultivation. Heather plants invaded on degraded forest soils and heaths developed. People learned to use the heaths for economic and cultural purposes. The impact of the heath management on landscape and soils was registered in soil records of barrows, drift sand sequences and plaggic Anthrosols. Based on pollen diagrams of such records we could reconstruct that heaths were developed and used for cattle grazing before the Bronze Age. During the Late Neolithic, the Bronze Age and Iron Age, people created the barrow landscape on the ancestral heaths. After the Iron Age people probably continued with cattle grazing on the heaths and plaggic agriculture until the Early Middle Ages. After 1000 AD two events affected the heaths. At first deforestation for the sale of wood resulted in the first regional extension of sand drifting and heath degradation. After that the introduction of the deep stable economy and heath sods digging resulted in acceleration of the rise of plaggic horizons, severe heath degradation and the second extension of sand drifting. At the end of the 19th century the heath lost its economic value due to the introduction of chemical fertilizers. The heaths were transformed into 'new' arable fields and forests and due to deep ploughing most soil archives were destroyed. Since 1980 AD, the remaining relicts of the ancestral heaths are

  14. Fuel dynamics and fire behaviour in Australian mallee and heath vegetation

    Science.gov (United States)

    Juanita Myers; Jim Gould; Miguel Cruz; Meredith Henderson

    2007-01-01

    In southern Australia, shrubby heath vegetation together with woodlands dominated by multistemmed eucalypts (mallee) comprise areas of native vegetation with important biodiversity values. These vegetation types occur in semiarid and mediterranean climates and can experience large frequent fires. This study is investigating changes in the fuel complex with time, fuel...

  15. 2015-2016 Travel and Hospitality Expense Reports for Alanna Heath

    International Development Research Centre (IDRC) Digital Library (Canada)

    Ruxandra Staicu

    Purpose: Board meetings. Date(s):. 2015-07-13 to 2015-07-14. Destination(s):. Ottawa. Airfare: $448.24. Other. Transportation: $115.45. Accommodation: $344.56. Meals and. Incidentals: $3.95. Other: Total: $912.20 ... and Hospitality Expense. Reports for Alanna Heath - Governor,. Chairperson of the Finance and Audit.

  16. System design and equipment reliability for wide web working at Hem Heath Colliery

    Energy Technology Data Exchange (ETDEWEB)

    Hall, L

    1982-02-01

    This paper outlines the challenge to mining engineers on system design and reliability of equipment and how Hem Heath Colliery in the UK, is meeting this challenge, by describing current systems of work and equipment on the faces, summarising experience gained with succeeding faces, the results achieved, and posing considerations for the future.

  17. Heaths and forests of the western hills of Chia, Bogota savanna, Colombia

    International Nuclear Information System (INIS)

    Cortes S, Sandra P.; Van der Hammen, Thomas; Rangel Ch, J Orlando

    2000-01-01

    The authors make a study of the heaths and forests of the western hills of the population of Chia, located in the savanna of Bogota and the presence or absences of these in the same Bogota savanna; the authors treat topics like their physiognomy and composition, distribution and ecology among other topics

  18. [Effects of tree species diversity on fine-root biomass and morphological characteristics in subtropical Castanopsis carlesii forests].

    Science.gov (United States)

    Wang, Wei-Wei; Huang, Jin-Xue; Chen, Feng; Xiong, De-Cheng; Lu, Zheng-Li; Huang, Chao-Chao; Yang, Zhi-Jie; Chen, Guang-Shui

    2014-02-01

    Fine roots in the Castanopsis carlesii plantation forest (MZ), the secondary forest of C. carlesii through natural regeneration with anthropogenic promotion (AR), and the secondary forest of C. carlesii through natural regeneration (NR) in Sanming City, Fujian Province, were estimated by soil core method to determine the influence of tree species diversity on biomass, vertical distribution and morphological characteristics of fine roots. The results showed that fine root biomass for the 0-80 cm soil layer in the MZ, AR and NR were (182.46 +/- 10.81), (242.73 +/- 17.85) and (353.11 +/- 16.46) g x m(-2), respectively, showing an increased tendency with increasing tree species diversity. In the three forests, fine root biomass was significantly influenced by soil depth, and fine roots at the 0-10 cm soil layer accounted for more than 35% of the total fine root biomass. However, the interaction of stand type and soil depth on fine-root distribution was not significant, indicating no influence of tree species diversity on spatial niche segregation in fine roots. Root surface area density and root length density were the highest in NR and lowest in the MZ. Specific root length was in the order of AR > MZ > NR, while specific root surface area was in the order of NR > MZ > AR. There was no significant interaction of stand type and soil depth on specific root length and specific root surface area. Fine root morphological plasticity at the stand level had no significant response to tree species diversity.

  19. Quantifying the Impact of Different Ways to Delimit Study Areas on the Assessment of Species Diversity of an Urban Forest

    Directory of Open Access Journals (Sweden)

    Rongxiao He

    2016-02-01

    Full Text Available Assessing the species diversity of an urban forest is important for understanding its structure and functions, but the result can be affected by sampling methods, times, and delimitations of the study area. In this study, we examined the influence of different ways to delimit boundaries of urban areas on the assessment of species diversity of urban forests through a case study conducted in Haikou, China. We surveyed the species diversity of the urban forest in Haikou twice using the same sampling protocol but two commonly used delimitations of the urban area. The two surveys produced significantly different estimates of species richness of the urban forest. Recorded species richness was 228 (144 woody and 84 herbaceous species and 303 (164 woody and 139 herbaceous species for the first and the second survey, respectively. The rarefaction analysis indicated that species richness of woody plants recorded in the two surveys could converge by doubling the sample size, but species richness of herbaceous plants was significantly different between the two surveys at the 95% confidence interval even at three times the original sample size. The value of the Simpson dissimilarity index between the two surveys was 0.417 and 0.357 for woody and herbaceous plants respectively, which implied noticeable dissimilarity of species compositions of plant assemblages in the two areas. We concluded that the assessment of biodiversity of an urban forest can be affected significantly by how the boundary of an urban area is defined. Caution should be taken when comparing species diversities of urban forests reported in different studies, especially when richness measures are used.

  20. SPECIES DIVERSITY AND COMMUNITY STRUCTURE OF FRUIT-FEEDING BUTTERFLIES (LEPIDOPTERA: NYMPHALIDAE) IN AN EASTERN AMAZONIAN FOREST

    OpenAIRE

    MARTINS, LUCAS PEREIRA; ARAUJO JUNIOR, ELIAS DA COSTA; MARTINS, ANANDA REGINA PEREIRA; DUARTE, MARCELO; AZEVEDO, GISELE GARCIA

    2017-01-01

    ABSTRACT Deforestation has negative impacts on diversity and community patterns of several taxa. In the eastern Amazon, where much deforestation is predicted for the coming years, forests patches may be essential to maintain the local biodiversity. Despite increasing concerns about the conservation of threatened areas, few studies have been performed to analyze the communities of diversified groups, such as insects, in the eastern Amazon. Here, we investigated species diversity and community ...

  1. Impacts of Bush Encroachment on Wildlife Species Diversity, Composition, and Habitat Preference in Ol Pejeta Conservancy, Laikipia, Kenya

    Directory of Open Access Journals (Sweden)

    Cyrus M. Kavwele

    2017-01-01

    Full Text Available Savannah ecosystems are currently facing a biome shift that changes grasslands to woody dominated landscapes, attributable to habitat degradation. In Ol Pejeta Conservancy (OPC, Euclea divinorum, an unpalatable and invasive woody species, is expanding to former savannah ecosystems with potential effects on herbivores key resources, wildlife species diversity, composition, and habitat use. We investigated wildlife species diversity, composition, and habitat preference or avoidance by wildlife in the conservancy. Infrared camera traps were deployed at the centroids of 2 km by 2 km, 50 cm above ground surface for 14 days and nights with 9 camera traps in each habitat type. Shannon wiener index revealed that wildlife species diversity was highest in E. divinorum dominated habitats and lowest in open grassland. Hierarchical Cluster Analysis revealed level of similarity in wildlife species composition between E. divinorum and mixed bushland. Jacobs index revealed that E. divinorum and mixed bushland were avoided by all guilds; however E. divinorum was significantly avoided while A. drepanolobium and open grassland were both preferred by all guilds. However, A. drepanolobium dominated habitats were significantly preferred compared to open grasslands. The findings are useful in management of sustainable ecosystems.

  2. Measurement of quantitative species diversity on reclaimed coal mine lands: A brief overview of the Wyoming regulatory proposal

    International Nuclear Information System (INIS)

    Vincent, R.B.

    1998-01-01

    The Wyoming Land Quality Division (LQD) Coal Rules and Regulations require mine operators to specify quantitative procedures for evaluating postmining species diversity and composition. Currently, permit commitments range from deferring to commit to a quantitative procedure until some future date to applying various similarity/diversity indices for comparison of reclaimed lands to native vegetation communities. Therefore, the LQD began trying to develop a standardized procedure to evaluate species diversity and composition, while providing operator flexibility. Review of several technical publications on the use of similarity and diversity indices, and other measurement techniques indicate that a consensus has not been reached on which procedure is most appropriate for use on reclaimed mine lands. In addition, implementation of many of the recommended procedures are not practical with regards to staff and data limitations. As a result, the LQD has developed an interim procedure, based on site-specific baseline data, to evaluate postmining species diversity and composition success with respect to bond release requests. This paper reviews many of the recommended procedures, outlines some of the pros and cons, and provides a specific example of how the proposed interim procedure was applied to an actual coal mine permit. Implementation of this or a similar procedure would allow for site-specific standardization of permits and regulatory requirements, thus reducing review time and reducing some of the subjectivity surrounding a component of the Wyoming bond release requirements

  3. Woody species diversity in forest plantations in a mountainous region of Beijing, China: effects of sampling scale and species selection.

    Directory of Open Access Journals (Sweden)

    Yuxin Zhang

    Full Text Available The role of forest plantations in biodiversity conservation has gained more attention in recent years. However, most work on evaluating the diversity of forest plantations focuses only on one spatial scale; thus, we examined the effects of sampling scale on diversity in forest plantations. We designed a hierarchical sampling strategy to collect data on woody species diversity in planted pine (Pinus tabuliformis Carr., planted larch (Larix principis-rupprechtii Mayr., and natural secondary deciduous broadleaf forests in a mountainous region of Beijing, China. Additive diversity partition analysis showed that, compared to natural forests, the planted pine forests had a different woody species diversity partitioning pattern at multi-scales (except the Simpson diversity in the regeneration layer, while the larch plantations did not show multi-scale diversity partitioning patterns that were obviously different from those in the natural secondary broadleaf forest. Compare to the natural secondary broadleaf forests, the effects of planted pine forests on woody species diversity are dependent on the sampling scale and layers selected for analysis. Diversity in the planted larch forest, however, was not significantly different from that in the natural forest for all diversity components at all sampling levels. Our work demonstrated that the species selected for afforestation and the sampling scales selected for data analysis alter the conclusions on the levels of diversity supported by plantations. We suggest that a wide range of scales should be considered in the evaluation of the role of forest plantations on biodiversity conservation.

  4. Species diversity and drivers of arbuscular mycorrhizal fungal communities in a semi-arid mountain in China

    Directory of Open Access Journals (Sweden)

    He Zhao

    2017-12-01

    Full Text Available Arbuscular mycorrhizal fungi (AMF play an essential role in complex ecosystems. However, the species diversity and composition of AMF communities remain unclear in semi-arid mountains. Further, it is not well understood if the characteristics of AMF community assemblies differ for different habitat types, e.g., agricultural arable land, artificial forest land, natural grassland, and bush/wood land. Here, using the high-throughput technology by Illumina sequencing on the MiSeq platform, we explored the species diversity and composition of soil AMF communities among different habitat types in a semi-arid mountain (Taihang Mountain, Mid-western region of China. Then, we analyzed the effect of nutrient composition and soil texture on AMF community assembly. Our results showed that members of the Glomus genera were predominated in all soil types. The distance-based redundancy analysis indicated that the content of water, available phosphorus, and available potassium were the most crucial geochemical factors that significantly affected AMF communities (p < 0.05. The analysis of the soil texture confirmed that AMF diversity was negatively correlated with soil clay content. The comparison of AMF diversity among the various habitat types revealed that the artificial forest land had the lowest AMF diversity in comparison with other land types. Our findings suggest that there were differences in species diversity and composition of soil AMF communities among different habitat types. These findings shed new light on the characteristics of community structure and drivers of community assembly in AMF in semi-arid mountains, and point to the potential importance of different habitat types on AMF communities.

  5. Rapport de frais de 2015-2016 pour Alanna Heath | CRDI - Centre ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Accueil · À propos du CRDI · Obligation de rendre compte · Transparence · Déplacements et accueil. Rapport de frais de 2015-2016 pour Alanna Heath. Total des frais de déplacement : CAD$912.20. Réunion du Conseil des gouverneurs. 13 juillet 2015 au 14 juillet 2015. CAD$912.20. Ce que nous faisons · Financement ...

  6. Dr. Robert G. Heath: a controversial figure in the history of deep brain stimulation.

    Science.gov (United States)

    O'Neal, Christen M; Baker, Cordell M; Glenn, Chad A; Conner, Andrew K; Sughrue, Michael E

    2017-09-01

    The history of psychosurgery is filled with tales of researchers pushing the boundaries of science and ethics. These stories often create a dark historical framework for some of the most important medical and surgical advancements. Dr. Robert G. Heath, a board-certified neurologist, psychiatrist, and psychoanalyst, holds a debated position within this framework and is most notably remembered for his research on schizophrenia. Dr. Heath was one of the first physicians to implant electrodes in deep cortical structures as a psychosurgical intervention. He used electrical stimulation in an attempt to cure patients with schizophrenia and as a method of conversion therapy in a homosexual man. This research was highly controversial, even prior to the implementation of current ethics standards for clinical research and often goes unmentioned within the historical narrative of deep brain stimulation (DBS). While distinction between the modern practice of DBS and its controversial origins is necessary, it is important to examine Dr. Heath's work as it allows for reflection on current neurosurgical practices and questioning the ethical implication of these advancements.

  7. Assessment of intra-species diversity among strains of Acinetobacter baumannii isolated from sites contaminated with petroleum hydrocarbons

    International Nuclear Information System (INIS)

    Manab Sarma, P.; Bhattacharya, D.; Krishnan, S.; Lal, B.

    2004-01-01

    Intra-species diversity among Acinetobacter baumannii strains isolated from crude oil-contaminated soils from different geographic regions in India was assessed, including their capability to degrade different fractions of total petroleum hydrocarbons. A total of 96 strains were isolated from five different sites. Of the 96 isolates, 25 strains were identified as Acinetobacter baumannii; all of these strains were biochemically profiled and grouped into eight phenovars on the basis of multivariate analysis of their substrate utilization profiles. All strains were able to degrade the total petroleum hydrocarbon fractions of crude oil. Intraspecies relatedness among the 25 strains was determined using tRNA intergenic spacer length polymorphism. Specific variants among the strains with different degradation capacities for different fractions of crude oil were detected. Environmental influences that cause intra-species diversity, such as functional resilience, within the selected strains of A. baumannii were also noted. It is suggested that such diversities may make it possible to select contaminant-specific strains for efficient biotechnological strategies in environmental remediation. 19 refs., 4 tabs., 3 figs

  8. Assessment of intra-species diversity among strains of Acinetobacter baumannii isolated from sites contaminated with petroleum hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Manab Sarma, P.; Bhattacharya, D.; Krishnan, S. [TERI School of Advanced Studies, Center of Bioresources and Biotechnology, New Delhi (India); Lal, B. [TERI School of Advanced Studies, Microbial Biotechnology Division, New Delhi (India)

    2004-06-01

    Intra-species diversity among Acinetobacter baumannii strains isolated from crude oil-contaminated soils from different geographic regions in India was assessed, including their capability to degrade different fractions of total petroleum hydrocarbons. A total of 96 strains were isolated from five different sites. Of the 96 isolates, 25 strains were identified as Acinetobacter baumannii; all of these strains were biochemically profiled and grouped into eight phenovars on the basis of multivariate analysis of their substrate utilization profiles. All strains were able to degrade the total petroleum hydrocarbon fractions of crude oil. Intraspecies relatedness among the 25 strains was determined using tRNA intergenic spacer length polymorphism. Specific variants among the strains with different degradation capacities for different fractions of crude oil were detected. Environmental influences that cause intra-species diversity, such as functional resilience, within the selected strains of A. baumannii were also noted. It is suggested that such diversities may make it possible to select contaminant-specific strains for efficient biotechnological strategies in environmental remediation. 19 refs., 4 tabs., 3 figs.

  9. Species diversity and seasonal variation in the composition of a bat community in the semi-arid brazilian caatinga

    Directory of Open Access Journals (Sweden)

    Patrício Adriano da Rocha

    2015-08-01

    Full Text Available The caatinga scrublands are relatively poorly-studied, and few data are available on the biome’s chiropteran fauna. The present study focuses on the bat community of the arboreal caatinga of Serra da Guia. Bats were trapped in mist-nets on three new moon nights per month between October, 2008, and September, 2009. Atotal of 157 individuals were captured, representing 12 species. Species richness estimated by Jackknife1 was 14.8. Glossophaga soricina and Carollia perspicillata were by far the most common species, accounting for 56.7% of the specimens captured. Species diversity was 1.80, while equitability was 0.72. There was no significant seasonal difference in species diversity or evenness. However, the present study recorded a clear seasonal shift in community structure. The principal difference in species composition was related to the temporal distribution of the rarest forms – all of the seven rarest species were recorded exclusively in only one season (dry or wet. The nectarivorous bats predominated numerically both in the dry season as in rainy, while frugivores became prominent, in terms of both the number of species and individuals, during the wet season. The predominance of stenodermatine bats during the wet season almost certainly reflects the increased availability of resources for this group during this part of the year.

  10. UV-absorbing compounds in subarctic herbarium bryophytes

    Energy Technology Data Exchange (ETDEWEB)

    Huttunen, S. [Botany Division, Department of Biology, P.O. Box 3000, FIN-90 014 University of Oulu (Finland)]. E-mail: satu.huttunen@oulu.fi; Lappalainen, N.M. [Botany Division, Department of Biology, P.O. Box 3000, FIN-90 014 University of Oulu (Finland); Turunen, J. [Botany Division, Department of Biology, P.O. Box 3000, FIN-90 014 University of Oulu (Finland)

    2005-01-01

    The UV-B-absorbing compounds of herbarium specimens of 10 subarctic bryophyte species collected during the years 1926-1996 and available at the Botanical Museum, University of Oulu, were studied. We studied whether herbarium specimens reflect changes in the past radiation climate through their methanol-extractable compounds. The order of gametophytes based on the average amount of total compounds (sum of A{sub 280-320nm}) per mass from the lowest to the highest was Polytrichum commune, Pleurozium schreberi, Hylocomium splendens, Sphagnum angustifolium, Dicranum scoparium, Funaria hygrometrica, Sphagnum fuscum, Sphagnum warnstorfii, Sphagnum capillifolium and Polytrichastrum alpinum, and the amount of UV-B-absorbing compounds per specific surface area correlated with the summertime daily global radiation and latitude. P. alpinum, F. hygrometrica and three Sphagnum species seem to be good indicators for further studies. The amount of UV-B-absorbing compounds revealed no significant trends from the 1920s till the 1990s, with the exception of S. capillifolium, which showed a significant decreasing trend. - UV-B-absorbing compounds in subarctic herbarium bryophytes indicate the radiation climate of the collecting site and time.

  11. UV-absorbing compounds in subarctic herbarium bryophytes

    International Nuclear Information System (INIS)

    Huttunen, S.; Lappalainen, N.M.; Turunen, J.

    2005-01-01

    The UV-B-absorbing compounds of herbarium specimens of 10 subarctic bryophyte species collected during the years 1926-1996 and available at the Botanical Museum, University of Oulu, were studied. We studied whether herbarium specimens reflect changes in the past radiation climate through their methanol-extractable compounds. The order of gametophytes based on the average amount of total compounds (sum of A 280-320nm ) per mass from the lowest to the highest was Polytrichum commune, Pleurozium schreberi, Hylocomium splendens, Sphagnum angustifolium, Dicranum scoparium, Funaria hygrometrica, Sphagnum fuscum, Sphagnum warnstorfii, Sphagnum capillifolium and Polytrichastrum alpinum, and the amount of UV-B-absorbing compounds per specific surface area correlated with the summertime daily global radiation and latitude. P. alpinum, F. hygrometrica and three Sphagnum species seem to be good indicators for further studies. The amount of UV-B-absorbing compounds revealed no significant trends from the 1920s till the 1990s, with the exception of S. capillifolium, which showed a significant decreasing trend. - UV-B-absorbing compounds in subarctic herbarium bryophytes indicate the radiation climate of the collecting site and time

  12. Determining the age of CO2 Released From Mountain Birch Forest and Heath in Arctic Sweden

    Science.gov (United States)

    Hartley, I. P.; Garnett, M. H.; Hopkins, D. W.; Sommerkorn, M.; Wookey, P. A.

    2008-12-01

    Nuclear weapons testing released a large amount of 14C into the atmosphere during the mid 20th Century. This radiocarbon pulse provides a tracer that can be used to determine the age of C released from plants and soils. Such information is critical for predicting how terrestrial C storage will respond to global change. If respired CO2 is mainly modern, then respiration and photosynthesis are tightly coupled. In contrast, if older C is being mineralized then there is more potential for climate change to induce C loss. We carried out one of the first studies to measure seasonal variations in the 14C content of CO2 released from arctic ecosystems. Using molecular sieves, we trapped CO2 respired from a mountain birch forest and heath near Abisko, northern Sweden and measured 14C contents by accelerator mass spectrometry. CO2 was collected from both vegetated plots (control) and clipped and trenched plots (CT) on three occasions during the 2007 growing season. In addition, we used a new passive sampling technique to collect CO2 from the CT plots during winter 2007-2008. Assuming that the respired C was derived from post bomb sources (justifiable as the majority of each soil profile was enriched with bomb C), we estimated the age of the CO2 and how it changed during the year in response to changes in plant activity and key environmental drivers. On the heath, the mean age of the CO2 respired from the control plots increased from 4 to 6 years old during the growing season. The CO2 respired from the CT plots increased from 5 years old in early June to 11 years old by July, but then declined to 8 years old in September. The C released during winter was also 8 years old. In the Birch forest, the mean age of CO2 respired from the CT plots increased from 4 years old in late May to 8-9 years old during July and September. However, during winter, the CO2 released was >10 years old. In the control plots, the age of respired CO2 increased from being 1 year old in late May to 6

  13. Flourish or flush: effects of simulated extreme rainfall events on Sphagnum-dwelling testate amoebae in a subarctic bog (Abisko, Sweden).

    Science.gov (United States)

    Tsyganov, Andrey N; Keuper, Frida; Aerts, Rien; Beyens, Louis

    2013-01-01

    Extreme precipitation events are recognised as important drivers of ecosystem responses to climate change and can considerably affect high-latitude ombrotrophic bogs. Therefore, understanding the relationships between increased rainfall and the biotic components of these ecosystems is necessary for an estimation of climate change impacts. We studied overall effects of increased magnitude, intensity and frequency of rainfall on assemblages of Sphagnum-dwelling testate amoebae in a field climate manipulation experiment located in a relatively dry subarctic bog (Abisko, Sweden). The effects of the treatment were estimated using abundance, species diversity and structure of living and empty shell assemblages of testate amoebae in living and decaying layers of Sphagnum. Our results show that increased rainfall reduced the mean abundance and species richness of living testate amoebae. Besides, the treatment affected species structure of both living and empty shell assemblages, reducing proportions of hydrophilous species. The effects are counterintuitive as increased precipitation-related substrate moisture was expected to have opposite effects on testate amoeba assemblages in relatively dry biotopes. Therefore, we conclude that other rainfall-related factors such as increased infiltration rates and frequency of environmental disturbances can also affect testate amoeba assemblages in Sphagnum and that hydrophilous species are particularly sensitive to variation in these environmental variables.

  14. The impact of ancestral heath management on soils and landscapes: a reconstruction based on paleoecological analyses of soil records in the central and southeastern Netherlands

    Science.gov (United States)

    Doorenbosch, Marieke; van Mourik, Jan M.

    2016-07-01

    The evolution of heathlands during the Holocene has been registered in various soil records. Paleoecological analyses of these records enable reconstruction of the changing economic and cultural management of heaths and the consequences for landscape and soils. Heaths are characteristic components of cultural landscape mosaics on sandy soils in the Netherlands. The natural habitat of heather species was moorland. At first, natural events like forest fires and storms caused small-scale forest degradation; in addition on that, the forest degradation accelerated due to cultural activities like forest grazing, wood cutting, and shifting cultivation. Heather plants invaded degraded forest soils, and heaths developed. People learned to use the heaths for economic and cultural purposes. The impact of the heath management on landscape and soils was registered in soil records of barrows, drift sand sequences, and plaggic Anthrosols. Based on pollen diagrams of such records we could reconstruct that heaths were developed and used for cattle grazing before the Bronze Age. During the late Neolithic, the Bronze Age, and Iron Age, people created the barrow landscape on the ancestral heaths. After the Iron Age, people probably continued with cattle grazing on the heaths and plaggic agriculture until the early Middle Ages. Severe forest degradation by the production of charcoal for melting iron during the Iron Age till the 6th-7th century and during the 11th-13th century for the trade of wood resulted in extensive sand drifting, a threat to the valuable heaths. The introduction of the deep, stable economy and heath sods digging in the course of the 18th century resulted in acceleration of the rise of plaggic horizons, severe heath degradation, and again extension of sand drifting. At the end of the 19th century heath lost its economic value due to the introduction of chemical fertilizers. The heaths were transformed into "new" arable fields and forests, and due to deep ploughing

  15. Enzymology under global change: organic nitrogen turnover in alpine and sub-Arctic soils

    NARCIS (Netherlands)

    Weedon, J.T.; Aerts, R.; Kowalchuk, G.A.; van Bodegom, P.M.

    2011-01-01

    Understanding global change impacts on the globally important carbon storage in alpine, Arctic and sub-Arctic soils requires knowledge of the mechanisms underlying the balance between plant primary productivity and decomposition. Given that nitrogen availability limits both processes, understanding

  16. Collembola at three alpine subarctic sites resistant to twenty years of experimental warming

    Czech Academy of Sciences Publication Activity Database

    Alatalo, J.M.; Jägerbrand, A.K.; Čuchta, Peter

    2015-01-01

    Roč. 5, December (2015), s. 18161 ISSN 2045-2322 Institutional support: RVO:60077344 Keywords : Collembola * alpine subarctic sites * experimental warming Subject RIV: EH - Ecology, Behaviour Impact factor: 5.228, year: 2015

  17. Enzymology under global change: organic nitrogen turnover in alpine and sub-Arctic soils.

    NARCIS (Netherlands)

    Weedon, J.T.; Aerts, R.; Kowalchuk, G.A.; van Bodegom, P.M.

    2011-01-01

    Understanding global change impacts on the globally important carbon storage in alpine, Arctic and sub-Arctic soils requires knowledge of the mechanisms underlying the balance between plant primary productivity and decomposition. Given that nitrogen availability limits both processes, understanding

  18. Climate vs. topography – spatial patterns of plant species diversity and endemism on a high-elevation island

    DEFF Research Database (Denmark)

    Irl, Severin David Howard; Harter, David E. V.; Steinbauer, Manuel

    2015-01-01

    the independent contribution of climatic and topographic variables to spatial diversity patterns. We constructed a presence/absence matrix of perennial endemic and native vascular plant species (including subspecies) in 890 plots on the environmentally very heterogeneous island of La Palma, Canary Islands......Climate and topography are among the most fundamental drivers of plant diversity. Here, we assessed the importance of climate and topography in explaining diversity patterns of species richness, endemic richness and endemicity on the landscape scale of an oceanic island and evaluated...... to ecological speciation and specialization to local conditions. We highlight the importance of incorporating climatic variability into future studies of plant species diversity and endemism. The spatial incongruence in hot spots of species richness, endemic richness and endemicity emphasizes the need...

  19. Energy Design Guidelines for High Performance Schools: Arctic and Subarctic Climates

    Energy Technology Data Exchange (ETDEWEB)

    2004-11-01

    The Energy Design Guidelines for High Performance Schools--Arctic and Subarctic Climates provides school boards, administrators, and design staff with guidance to help them make informed decisions about energy and environmental issues important to school systems and communities. These design guidelines outline high performance principles for the new or retrofit design of your K-12 school in arctic and subarctic climates. By incorporating energy improvements into their construction or renovation plans, schools can significantly reduce energy consumption and costs.

  20. Restoration of degraded drylands through exclosures enhancing woody species diversity and soil nutrients in the highlands of Tigray, Northern Ethiopia

    Directory of Open Access Journals (Sweden)

    Kide M. Gebremedihin

    2018-02-01

    Full Text Available Exclusion of grazing animals and tree plantations were among the methods used for the rehabilitation of degraded lands in tropical semiarid areas. Exclosures can foster secondary forest succession by improving soil conditions, attracting seed-dispersal agents and modifying microclimate for understory growth. This paper compares the woody species diversity and soil chemical properties under exclosure with increasing age and grazing land at different slope positions. The study has been conducted in northern Ethiopia from 12 exclosure sites paired each with adjacent grazing land with four treatments replicated three times. In the entire study 216 plots were examined of which 108 were in exclosures and 108 in communal grazing lands.There were four age classes and three slope positions in each of the landuses. Vegetation data were collected using plots measuring 100 m2. Soils for physicochemical properties were collected from the four corners and center of 5 × 5m plots which was inside the 10 × 10m plot. A total of 61 woody plant species belonging to 41 families were recorded. Diversity and species richness were higher in the exclosures than in grazing lands. Among exclosures these parameters were higher in exclosures older than 30 years and at the foot of the slope. Grazing lands, the youngest exclosures and upper elevation gradient recorded lower values. Chemical soil properties were significantly higher in the exclosures, among them in the oldest exclosures and at foot elevation (except for P than these were in the grazing land, the youngest exclosures and upper parts of slopes respectively. Exclosures are instrumental to improve the woody species diversity and soil chemical properties in the drylands.

  1. The Social Structure of Participants of the Battle of Blore Heath (September 23, 1459)

    OpenAIRE

    Andrey G. Prazdnikov

    2017-01-01

    The battle of Blore Heath which took place on September 23, 1459, marked the new stage of the Wars of Roses, which led to the change of dynasties at the English throne in less than two years. As it was not the clash of the main forces of House of Lancaster and House of York, the sources contain poor information about the battle’s participants. However, the analysis different sources let identify the names of 22 participants. Prosopographic study of this group contributes to the study of socia...

  2. Fluxes of Methane and Carbon Dioxide from a Subarctic Lake

    DEFF Research Database (Denmark)

    Jammet, Mathilde Manon

    ) and carbon dioxide (CO2) with the atmosphere. Yet uncertainties in the magnitude and drivers of these fluxes remain, partly due to a lack of direct observations covering all seasons of the year, but also because of the diversity in measurement methods that often miss components of the transport processes......Ongoing climate warming is expected to affect the carbon functioning of subarctic ecosystems. Lakes and wetlands, which are common ecosystems of the high northern latitudes, are of utmost interest in this context because they exchange large amounts of the climate-forcing gases methane (CH4......-out and the release of CH4 and CO2 was established. These results underline the crucial importance of shoulder seasons in the annual carbon emissions from seasonally frozen lakes. Overall, the lake was an important annual source of carbon to the atmosphere, partially compensating the higher, annual sink function...

  3. Recent dynamics of arctic and sub-arctic vegetation

    International Nuclear Information System (INIS)

    Epstein, Howard E; Myers-Smith, Isla; Walker, Donald A

    2013-01-01

    We present a focus issue of Environmental Research Letters on the ‘Recent dynamics of arctic and sub-arctic vegetation’. The focus issue includes three perspective articles (Verbyla 2011 Environ. Res. Lett. 6 041003, Williams et al 2011 Environ. Res. Lett. 6 041004, Loranty and Goetz 2012 Environ. Res. Lett. 7 011005) and 22 research articles. The focus issue arose as a result of heightened interest in the response of high-latitude vegetation to natural and anthropogenic changes in climate and disturbance regimes, and the consequences that these vegetation changes might have for northern ecosystems. A special session at the December 2010 American Geophysical Union Meeting on the ‘Greening of the Arctic’ spurred the call for papers. Many of the resulting articles stem from intensive research efforts stimulated by International Polar Year projects and the growing acknowledgment of ongoing climate change impacts in northern terrestrial ecosystems. (synthesis and review)

  4. Hydrology of two slopes in subarctic Yukon, Canada

    Science.gov (United States)

    Carey, Sean K.; Woo, Ming-Ko

    1999-11-01

    Two subarctic forested slopes in central Wolf Creek basin, Yukon, were studied in 1996-1997 to determine the seasonal pattern of the hydrologic processes. A south-facing slope has a dense aspen forest on silty soils with seasonal frost only and a north-facing slope has open stands of black spruce and an organic layer on top of clay sediments with permafrost. Snowmelt is advanced by approximately one month on the south-facing slope due to greater radiation receipt. Meltwater infiltrates its seasonally frozen soil with low ice content, recharging the soil moisture reservoir but yielding no lateral surface or subsurface flow. Summer evaporation depletes this recharged moisture and any additional rainfall input, at the expense of surface or subsurface flow. The north-facing slope with an ice rich substrate hinders deep percolation. Snow meltwater is impounded within the organic layer to produce surface runoff in rills and gullies, and subsurface flow along pipes and within the matrix of the organic soil. During the summer, most subsurface flows are confined to the organic layer which has hydraulic conductivities orders of magnitudes larger than the underlying boulder-clay. Evaporation on the north-facing slope declines as both the frost table and the water table descend in the summer. A water balance of the two slopes demonstrates that vertical processes of infiltration and evaporation dominate moisture exchanges on the south-facing slope, whereas the retardation of deep drainage by frost and by clayey soil on the permafrost slope promotes a strong lateral flow component, principally within the organic layer. These results have the important implication that permafrost slopes and organic horizons are the principal controls on streamflow generation in subarctic catchments.

  5. Human exposure to soil contaminants in subarctic Ontario, Canada

    Directory of Open Access Journals (Sweden)

    Ellen Stephanie Reyes

    2015-05-01

    Full Text Available Background: Chemical contaminants in the Canadian subarctic present a health risk with exposures primarily occurring via the food consumption. Objective: Characterization of soil contaminants is needed in northern Canada due to increased gardening and agricultural food security initiatives and the presence of known point sources of pollution. Design: A field study was conducted in the western James Bay Region of Ontario, Canada, to examine the concentrations of polychlorinated biphenyls, dichlorodiphenyltrichloroethane and its metabolites (ΣDDT, other organochlorines, and metals/metalloids in potentially contaminated agriculture sites. Methods: Exposure pathways were assessed by comparing the estimated daily intake to acceptable daily intake values. Ninety soil samples were collected at random (grid sampling from 3 plots (A, B, and C in Fort Albany (on the mainland, subarctic Ontario, Canada. The contaminated-soil samples were analysed by gas chromatography with an electron capture detector or inductively coupled plasma mass spectrometer. Results: The range of ΣDDT in 90 soil samples was below the limit of detection to 4.19 mg/kg. From the 3 soil plots analysed, Plot A had the highest ΣDDT mean concentration of 1.12 mg/kg, followed by Plot B and Plot C which had 0.09 and 0.01 mg/kg, respectively. Concentrations of other organic contaminants and metals in the soil samples were below the limit of detection or found in low concentrations in all plots and did not present a human health risk. Conclusions: Exposure analyses showed that the human risk was below regulatory thresholds. However, the ΣDDT concentration in Plot A exceeded soil guidelines set out by the Canadian Council of Ministers of the Environment of 0.7 mg/kg, and thus the land should not be used for agricultural or recreational purposes. Both Plots B and C were below threshold limits, and this land can be used for agricultural purposes.

  6. Soil fauna and leaf species, but not species diversity, affect initial soil erosion in a subtropical forest plantation

    Science.gov (United States)

    Seitz, Steffen; Goebes, Philipp; Assmann, Thorsten; Schuldt, Andreas; Scholten, Thomas

    2017-04-01

    In subtropical parts of China, high rainfall intensities cause continuous soil losses and thereby provoke severe harms to ecosystems. In woodlands, it is not the tree canopy, but mostly an intact forest floor that provides protection from soil erosion. Although the protective role of leaf litter covers against soil losses is known for a long time, little research has been conducted on the processes involved. For instance, the role of different leaf species and leaf species diversity has been widely disregarded. Furthermore, the impact of soil meso- and macrofauna within the litter layer on soil losses remains unclear. To investigate how leaf litter species and diversity as well as soil meso- and macrofauna affect sediment discharge in a subtropical forest ecosystem, a field experiment was carried out in Xingangshan, Jiangxi Province, PR China (BEF China). A full-factorial random design with 96 micro-scale runoff plots and seven domestic leaf species in three diversity levels and a bare ground feature were established. Erosion was initiated with a rainfall simulator. This study confirms that leaf litter cover generally protects forest soils from water erosion (-82 % sediment discharge on leaf covered plots compared to bare plots) and this protection is gradually removed as the litter layer decomposes. Different leaf species showed variable impacts on sediment discharge and thus erosion control. This effect can be related to different leaf habitus, leaf decomposition rates and food preferences of litter decomposing meso- and macrofauna. In our experiment, runoff plots with leaf litter from Machilus thunbergii in monoculture showed the highest sediment discharge (68.0 g m-2), whereas plots with Cyclobalanopsis glauca in monoculture showed the smallest rates (7.9 g m-2). At the same time, neither leaf species diversity, nor functional diversity showed any significant influence, only a negative trend could be observed. Nevertheless, the protective effect of the leaf

  7. Plant species diversity as a driver of early succession in abandoned fields: a multi-site approach.

    Science.gov (United States)

    Van der Putten, W H; Mortimer, S R; Hedlund, K; Van Dijk, C; Brown, V K; Lepä, J; Rodriguez-Barrueco, C; Roy, J; Diaz Len, T A; Gormsen, D; Korthals, G W; Lavorel, S; Regina, I Santa; Smilauer, P

    2000-07-01

    Succession is one of the most studied processes in ecology and succession theory provides strong predictability. However, few attempts have been made to influence the course of succession thereby testing the hypothesis that passing through one stage is essential before entering the next one. At each stage of succession ecosystem processes may be affected by the diversity of species present, but there is little empirical evidence showing that plant species diversity may affect succession. On ex-arable land, a major constraint of vegetation succession is the dominance of perennial early-successional (arable weed) species. Our aim was to change the initial vegetation succession by the direct sowing of later-successional plant species. The hypothesis was tested that a diverse plant species mixture would be more successful in weed suppression than species-poor mixtures. In order to provide a robust test including a wide range of environmental conditions and plant species, experiments were carried out at five sites across Europe. At each site, an identical experiment was set up, albeit that the plant species composition of the sown mixtures differed from site to site. Results of the 2-year study showed that diverse plant species mixtures were more effective at reducing the number of natural colonisers (mainly weeds from the seed bank) than the average low-diversity treatment. However, the effect of the low-diversity treatment depended on the composition of the species mixture. Thus, the effect of enhanced species diversity strongly depended on the species composition of the low-diversity treatments used for comparison. The effects of high-diversity plant species mixtures on weed suppression differed between sites. Low-productivity sites gave the weakest response to the diversity treatments. These differences among sites did not change the general pattern. The present results have implications for understanding biological invasions. It has been hypothesised that alien

  8. Chapter 16: Species Diversity

    African Journals Online (AJOL)

    zargaran

    2012-05-03

    May 3, 2012 ... rarefaction method was recorded in Pardanan, with 28 oak gall wasps species. Furthermore, the highest amount of Gini-Simpson and Shannon entropy index were recorded in Sardasht, while the highest evenness was recorded in Shalmash. Differences in the local distribution of oak species, especially.

  9. Preliminary study of Malaysian fruit bats species diversity in Lenggong Livestock Breeding Center, Perak: Potential risk of spill over infection

    Directory of Open Access Journals (Sweden)

    Muhammed Mikail

    2017-11-01

    Full Text Available Aim: Farms that are neighboring wildlife sanctuaries are at risk of spillover infection from wildlife, and the objective of this research is to examine the species diversity of Malaysian fruit bats in livestock farm in determining the possible risk of spill over infection to livestock. Materials and Methods: Fifty individual fruit bats were captured using six mists net, from May to July 2017. The nets were set at dusk (1830 h as bats emerge for foraging and monitored at every 30-min intervals throughout the night until dawn when they returned to the roost. The nets were closed for the day until next night, and captured bats were identified to species levels. Results: All the captured bats were mega chiropterans, and Cynopterus brachyotis was the highest captured species, representing 40% of the total capture. Shannon-Weiner index is 2.80, and Simpson index is 0.2. Our result suggests that there is a degree of species dominance with low diversity in Lenggong Livestock Breeding Center. Conclusion: We concluded that fruit bats are indeed, encroaching livestock areas and the species identified could be a potential source of infection to susceptible livestock. Hence, an active surveillance should be embarked on farms that border wildlife sanctuaries.

  10. Sandfly species diversity in association with human activities in the Kani tribe settlements of the Western Ghats, Thiruvananthapuram, Kerala, India

    Directory of Open Access Journals (Sweden)

    Srinivasan Ranganathan

    2015-04-01

    Full Text Available Sandfly prevalence in the Kani tribe settlements of Western Ghats in India was investigated. A total of 1,279 sandflies comprising 17 species was obtained. Sandfly abundance showed a negative correlation (r = -0.97, p = 0.003 with increase in altitudinal ranges from 0-1,000 m. When sandfly samples were grouped according to landscape characteristics of the location, the estimated Shannon-Weiner index (H and species richness index (S were high and species evenness index (J was low in settlements located at 0-300 m altitudinal range. On the contrary, the values of H and J were high, while S was low at 301-600 m altitudinal range. With further increase in altitude, species diversity, S and J were low. Though the relative abundance of sandflies decreased with increase in altitude, the influence of altitudinal variation could not be attributed to determine sandfly diversity, since the number of sampling units were not uniform at all the altitudinal gradients due to nonavailability of suitable resting shelters. Sandfly species showed great aggregation at 0-300 m altitude interval, where not only the number of settlements were maximum (n = 19, but also the environmental conditions favoured sandfly abundance due to the concentration of tribal settlements, human dwellings and his activities.

  11. Species diversity, vegetation pattern and conservation of Gentiana macrophylla Pall. communities in Dongling mountain meadow, Beijing, China

    International Nuclear Information System (INIS)

    Sadia, S.; Zhang, J.T.; Bai, X.; Shedayi, A.A.; Tariq, A.

    2017-01-01

    Gentiana macrophylla, native to mountainous areas of Central and Southern Asia, is most popular remedy for rheumatism and pains in Traditional Chinese Medicine with an extensive demand in local market. Our study aimed to classify G. macrophylla communities and to find out the impact of topographic and soil factors on their diversity and distribution in Dongling mountain meadow, Beijing, China. Seventy five samples in 15 transects separated by 50m distance in altitude along an elevation gradient (1592-2298m) were established by quadrate method. TWINSAPN and CCA were used for classification and ordination, respectively. Six diversity indices (Species richness, Shannon-Weiner heterogeneity, Simpson’s index, Hill’s index, Pielou evenness and McIntosh evenness) were used to analyze the pattern of species diversity and polynomial regression analysis was used to establish their relationship with environmental variables. TWINSPAN classified G. macrophylla communities into 8 types and CCA indicated that soil pH, soil temperature, soil type, disturbance, total N, total K, Mg and Zn were significantly related to these communities. Elevation was the most significant factor that affecting the diversity and distribution of G. macrophylla communities. Significant effect of environment, topography and disturbance to meadow communities of G. macrophylla highly suggests some important measures such as uprooting restriction, tourism limitation in meadow area, monitoring of functional diversity, fertilization, irrigation, cloning and cultivation to protect and conserve it and its communities to be used in medicine industry. (author)

  12. Sandfly species diversity in association with human activities in the Kani tribe settlements of the Western Ghats, Thiruvananthapuram, Kerala, India.

    Science.gov (United States)

    Ranganathan, Srinivasan; Swaminathan, Subramanian

    2015-04-01

    Sandfly prevalence in the Kani tribe settlements of Western Ghats in India was investigated. A total of 1,279 sandflies comprising 17 species was obtained. Sandfly abundance showed a negative correlation (r = -0.97, p = 0.003) with increase in altitudinal ranges from 0-1,000 m. When sandfly samples were grouped according to landscape characteristics of the location, the estimated Shannon-Weiner index (H) and species richness index (S) were high and species evenness index (J) was low in settlements located at 0-300 m altitudinal range. On the contrary, the values of H and J were high, while S was low at 301-600 m altitudinal range. With further increase in altitude, species diversity, S and J were low. Though the relative abundance of sandflies decreased with increase in altitude, the influence of altitudinal variation could not be attributed to determine sandfly diversity, since the number of sampling units were not uniform at all the altitudinal gradients due to nonavailability of suitable resting shelters. Sandfly species showed great aggregation at 0-300 m altitude interval, where not only the number of settlements were maximum (n = 19), but also the environmental conditions favoured sandfly abundance due to the concentration of tribal settlements, human dwellings and his activities.

  13. Woody Species Diversity in Traditional Agroforestry Practices of Dellomenna District, Southeastern Ethiopia: Implication for Maintaining Native Woody Species

    Directory of Open Access Journals (Sweden)

    Abiot Molla

    2015-01-01

    Full Text Available The major impact of humans on forest ecosystems including loss of forest area, habitat fragmentation, and soil degradation leads to losses of biodiversity. These problems can be addressed by integration of agriculture with forests and maintaining the existing forests. This study was initiated to assess woody species diversity of traditional agroforestry practices. Three study sites (Burkitu, Chire, and Erba were selected based on the presence of agroforestry practice. Forty-eight (48 sample quadrants having an area of 20 m × 20 m, 16 sample quadrants in each study site, were systematically laid using four transect lines at different distance. The diversity of woody species was analyzed by using different diversity indices. A total of 55 woody species belonging to 31 families were identified and documented. There were significantly different (P<0.05 among the study Kebeles (peasant associations. Mangifera indica, Entada abyssinica, and Croton macrostachyus were found to have the highest Important Value Index. The results confirmed that traditional agroforestry plays a major role in the conservation of native woody species. However, threats to woody species were observed. Therefore, there is a need to undertake conservation practices before the loss of species.

  14. SPECIES DIVERSITY AND COMMUNITY STRUCTURE OF FRUIT-FEEDING BUTTERFLIES (LEPIDOPTERA: NYMPHALIDAE IN AN EASTERN AMAZONIAN FOREST

    Directory of Open Access Journals (Sweden)

    LUCAS PEREIRA MARTINS

    Full Text Available ABSTRACT Deforestation has negative impacts on diversity and community patterns of several taxa. In the eastern Amazon, where much deforestation is predicted for the coming years, forests patches may be essential to maintain the local biodiversity. Despite increasing concerns about the conservation of threatened areas, few studies have been performed to analyze the communities of diversified groups, such as insects, in the eastern Amazon. Here, we investigated species diversity and community structure of fruit-feeding butterflies, a well-known bioindicator group, in a threatened remnant of an eastern Amazonian forest located on Maranhão Island, northeastern Brazil. Fruit-feeding butterflies were sampled monthly for one year. Diversity and evenness indices, richness estimators, rarefaction curve, and rank-abundance plot were used to describe community structure in the study area. We captured 529 fruit-feeding butterflies in four subfamilies, 23 genera and 34 species. The three most abundant species, Hamadryas februa, Hamadryas feronia, and Hermeuptychia cf. atalanta are indicators of disturbed habitats and represented more than half of the collected individuals. Richness estimators revealed that between 87 and 94% of the fruit-feeding butterfly species were sampled, suggesting few additional records would be made for the area. Our results indicate that human-caused disturbances have altered local community patterns and provide baseline data for future research in threatened regions of the eastern Amazon.

  15. Scale Expansion of Community Investigations and Integration of the Effects of Abiotic and Biotic Processes on Maintenance of Species Diversity

    Directory of Open Access Journals (Sweden)

    Zhenhong Wang

    2011-01-01

    Full Text Available Information on the maintenance of diversity patterns from regional to local scales is dispersed among academic fields due to the local focus of community ecology. To better understand these patterns, the study of ecological communities needs to be expanded to larger scales and the various processes affecting them need to be integrated using a suitable quantitative method. We determined a range of communities on a flora-subregional scale in Yunnan province, China (383210.02 km2. A series of species pools were delimited from the regional to plot scales. Plant diversity was evaluated and abiotic and biotic processes identified at each pool level. The species pool effect was calculated using an innovative model, and the contribution of these processes to the maintenance of plant species diversity was determined and integrated: climate had the greatest effect at the flora-subregional scale, with historical and evolutionary processes contributing ∼11%; climate and human disturbance had the greatest effect at the local site pool scale; competition exclusion and stress limitation explained strong filtering at the successional stage pool scale; biotic processes contributed more on the local community scale than on the regional scale. Scale expansion combined with the filtering model approach solves the local problem in community ecology.

  16. UREDINALES (RUST FUNGI BIOTA OF THE PARQUE NACIONAL DO ITATIAIA, BRAZIL: AN ANALYSIS OF COMPOSITION, SPECIES DIVERSITY AND ALTITUDINAL DISTRIBUTION

    Directory of Open Access Journals (Sweden)

    Salazar Yepes Mauricio

    2013-07-01

    Full Text Available The present study analyzed the composition, species diversity, and altitudinal distributionof rust fungi (Uredinales collected in the Parque Nacional do Itatiaia, Brazil.Results were compared with other Atlantic Forest locations, the São Paulo Cerradoand some other tropical regions. The Uredinales collections were made over thecourse of two years, covering the states of Rio de Janeiro and Minas Gerais, from500 to 2600m above the sea level. The Uredinales Biota is composed of 38 genera(32 teleomorphs and 6 anamorphs and 207 species, 178 of which were teleomorphicand 29 anamorphic. The genera Puccinia, Uromyces and Phakopsora contained ahigh number of species (58% combined. A hundred and ninety-two hosts belongingto 63 botanical families were recorded. The rust/host ratio for ten of the richestfamilies in number of species was 1:8. A high similarity (50% was found betweentwo altitudinal ranges. The results provide a strong additional argument for the needto preserve and continue studies in such areas

  17. Tapeworms (Cestoda: Proteocephalidea) of teleost fi shes from the Amazon River in Peru: additional records as an evidence of unexplored species diversity

    Czech Academy of Sciences Publication Activity Database

    de Chambrier, A.; Kuchta, Roman; Scholz, Tomáš

    2015-01-01

    Roč. 122, č. 1 (2015), s. 149-163 ISSN 0035-418X R&D Projects: GA ČR GBP505/12/G112 Institutional support: RVO:60077344 Keywords : Catfish * freshwater fish * Siluriformes * Peru * Pimelodidae * Amazonia * species diversity * faunal survey Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 0.431, year: 2015

  18. Permafrost Thaw increases Emissions of Nitrous Oxide from Subarctic Peatlands

    Science.gov (United States)

    Voigt, C.; Marushchak, M. E.; Lamprecht, R. E.; Jackowicz-Korczynski, M.; Lindgren, A.; Mastepanov, M.; Christensen, T. R.; Granlund, L.; Tahvanainen, T.; Martikainen, P. J.; Biasi, C.

    2017-12-01

    Permafrost soils in the Arctic are thawing, exposing not only carbon but also large nitrogen stocks. The decomposition of this vast pool of long-term immobile C and N stocks results in the release of greenhouse gases to the atmosphere. Among these, carbon dioxide (CO2) and methane (CH4) are being studied extensively, and gaseous C release from thawing permafrost is known to be substantial. Most recent studies, however, show that Arctic soils may further be a relevant source of the strong greenhouse gas nitrous oxide (N2O). As N2O is almost 300 times more powerful in warming the climate than CO2 based on a 100-yr time horizon, the release of N2O from thawing permafrost could create a significant non-carbon permafrost-climate feedback. To study the effect of permafrost thaw on N2O fluxes, we collected peat mesocosms from a Subarctic permafrost peatland, and subjected these intact soil-plant systems to sequential thawing from the top of the active layer down to the upper permafrost layer. Measurements of N2O fluxes were coupled with detailed soil analyses and process studies. Since N2O fluxes are highly dependent on moisture conditions and vegetation cover, we applied two distinct moisture treatments (dry vs. wet) and simulated permafrost thaw in vegetated as well as in naturally bare mesocosms. Under dry conditions, permafrost thaw clearly increased N2O emissions. We observed the largest post-thaw emissions from bare peat surfaces, a typical landform in subarctic peatlands previously identified as hot spots for Arctic N2O emissions. There, permafrost thaw caused a five-fold increase in emissions (0.56 vs. 2.81 mg N2O m-2 d-1). While water-logged conditions suppressed N2O emissions, the presence of vegetation lowered, but did not prevent post-thaw N2O release. Based on these findings, we show that one fourth of the Arctic land area could be vulnerable for N2O emissions when permafrost thaws. Our results demonstrate that Arctic N2O emissions may be larger than

  19. Ecohydrological Controls on Intra-Basin Alpine Subarctic Water Balances

    Science.gov (United States)

    Carey, S. K.; Ziegler, C. M.

    2007-12-01

    In the mountainous Canadian subarctic, elevation gradients control the disposition of vegetation, permafrost, and characteristics of the soil profile. How intra-basin ecosystems combine to control catchment-scale water and biogeochimcal cycling is uncertain. To this end, a multi-year ecohydrological investigation was undertaken in Granger Basin (GB), a 7.6 km2 sub-basin of the Wolf Creek Research Basin, Yukon Territory, Canada. GB was divided into four sub-basins based on the dominant vegetation and permafrost status, and the timing and magnitude of hydrological processes were compared using hydrometric and hydrochemical methods. Vegetation plays an important role in end-of-winter snow accumulation as snow redistribution by wind is controlled by roughness length. In sub-basins of GB with tall shrubs, snow accumulation is enhanced compared with areas of short shrubs and tundra vegetation. The timing of melt was staggered with elevation, although melt-rates were similar among the sub-basins. Runoff was enhanced at the expense of infiltration in tall shrub areas due to high snow water equivalent and antecedent soil moisture. In the high-elevation tundra sub-basin, thin soils with cold ground temperatures resulted in increased surface runoff. For the freshet period, the lower and upper sub-basins accounted for 81 % of runoff while accounting for 58 % of the total basin area. Two-component isotopic hydrograph separation revealed that during melt, pre-event water dominated in all sub-basins, yet those with greater permafrost disposition and taller shrubs had increased event-water. Dissolved organic carbon (DOC) spiked prior to peak freshet in each sub-basin except for the highest with thin soils, and was associated with flushing of surficial organic soils. For the post-melt period, all sub-basins have similar runoff contributions. Solute and stable isotope data indicate that in sub-basins dominated by permafrost, supra-permafrost runoff pathways predominate as flow

  20. Disentangling the effects of species diversity, and intraspecific and interspecific tree size variation on aboveground biomass in dry zone homegarden agroforestry systems.

    Science.gov (United States)

    Ali, Arshad; Mattsson, Eskil

    2017-11-15

    The biodiversity - aboveground biomass relationship has been intensively studied in recent decades. However, no consensus has been arrived to consider the interplay of species diversity, and intraspecific and interspecific tree size variation in driving aboveground biomass, after accounting for the effects of plot size heterogeneity, soil fertility and stand quality in natural forest including agroforests. We tested the full, partial and no mediations effects of species diversity, and intraspecific and interspecific tree size variation on aboveground biomass by employing structural equation models (SEMs) using data from 45 homegarden agroforestry systems in Sri Lanka. The full mediation effect of either species diversity or intraspecific and interspecific tree size variation was rejected, while the partial and no mediation effects were accepted. In the no mediation SEM, homegarden size had the strongest negative direct effect (β=-0.49) on aboveground biomass (R 2 =0.65), followed by strong positive direct effect of intraspecific tree size variation (β=0.32), species diversity (β=0.29) and interspecific tree size variation (β=0.28). Soil fertility had a negative direct effect on interspecific tree size variation (β=-0.31). Stand quality had a significant positive total effect on aboveground biomass (β=0.28), but homegarden size had a significant negative total effect (β=-0.62), while soil fertility had a non-significant total effect on aboveground biomass. Similar to the no mediation SEM, the partial mediation SEMs had explained almost similar variation in aboveground biomass because species diversity, and intraspecific and interspecific tree size variation had non-significant indirect effects on aboveground biomass via each other. Our results strongly suggest that a multilayered tree canopy structure, due to high intraspecific and interspecific tree size variation, increases light capture and efficient utilization of resources among component species, and

  1. The impact of climate change on ecosystem carbon dynamics at the Scandinavian mountain birch forest-tundra heath ecotone.

    Science.gov (United States)

    Sjögersten, Sofie; Wookey, Philip A

    2009-02-01

    Changes in temperature and moisture resulting from climate change are likely to strongly modify the ecosystem carbon sequestration capacity in high-latitude areas, both through vegetation shifts and via direct warming effects on photosynthesis and decomposition. This paper offers a synthesis of research addressing the potential impacts of climate warming on soil processes and carbon fluxes at the forest-tundra ecotone in Scandinavia. Our results demonstrated higher rates of organic matter decomposition in mountain birch forest than in tundra heath soils, with markedly shallower organic matter horizons in the forest. Field and laboratory experiments suggest that increased temperatures are likely to increase CO2 efflux from both tundra and forest soil providing moisture availability does not become limiting for the decomposition process. Furthermore, colonization of tundra heath by mountain birch forest would increase rates of decomposition, and thus CO2 emissions, from the tundra heath soils, which currently store substantial amounts of potentially labile carbon. Mesic soils underlying both forest and tundra heath are currently weak sinks of atmospheric methane, but the strength of this sink could be increased with climate warming and/or drying.

  2. Temperate heath plant response to dry conditions depends on growth strategy and less on physiology

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Kongstad, J.; Schmidt, I. K.

    2012-01-01

    of these differences in response in dry versus rewetting conditions can be used to highlight the limitations coherent in different strategies adopted by, for example, evergreen shrubs and grasses. We investigated the leaf-level photosynthetic performance, leaf C, N and d13C along with vegetation cover and biomass...... in the evergreen dwarf shrub Calluna vulgaris and the grass species Deschampsia flexuosa in a temperate heath during seasonal changes in soil moisture. Higher photosynthetic capacity compensated for lower stomatal conductance and sustained higher rates of photosynthesis in the grass compared to the dwarf shrub....... In combination with dieback of aboveground biomass and reduction of stomatal conductance reduction during dry conditions, the grass continued to have high carbon uptake in the remaining leaves. The dwarf shrub endured the dry conditions by preserving shoot biomass and reducing stomatal conductance. Soil...

  3. Glycine uptake in heath plants and soil microbes responds to elevated temperature, CO2 and drought

    DEFF Research Database (Denmark)

    Andresen, Luise C.; Michelsen, Anders; Jonasson, Sven

    2009-01-01

    the responses to single factors treatments. The soil microbes were superior to plants in the short-term competition for the added glycine, as indicated by an 18 times larger 15N recovery in the microbial biomass compared to the plant biomass. The soil microbes acquired glycine largely as an intact compound (87...... here present results from a field experiment in which the effects of these three climate change factors are investigated solely and in all combinations at a temperate heath dominated by heather (Calluna vulgaris) and wavy hair-grass (Deschampsia flexuosa). Climate induced increases in plant production...... may increase plant root exudation of dissolved organic compounds such as amino acids, and the release of amino acids during decomposition of organic matter. Such free amino acids in soil serve as substrates for soil microorganisms and are also acquired as nutrients directly by plants. We investigated...

  4. UDASH – Unified Database for Arctic and Subarctic Hydrography

    Directory of Open Access Journals (Sweden)

    A. Behrendt

    2018-06-01

    Full Text Available UDASH (Unified Database for Arctic and Subarctic Hydrography is a unified and high-quality temperature and salinity data set for the Arctic Ocean and the subpolar seas north of 65° N for the period 1980–2015. The archive aims at including all publicly available data and so far consists of 288 532 oceanographic profiles measured mainly with conductivity–temperature–depth (CTD probes, bottles, mechanical thermographs and expendable thermographs. The data were collected by ships, ice-tethered profilers, profiling floats and other platforms. To achieve a uniform quality level, suitable for a wide range of oceanographic analyses, approximately 74 million single measurements of temperature and salinity were thoroughly quality checked. A large number of duplicate and erroneous profiles were detected and not included in the archive. Data outliers were flagged for quick identification. The final archive provides a unique and simple way of accessing most of the available temperature and salinity data for the Arctic Ocean and can be downloaded from https://doi.pangaea.de/10.1594/PANGAEA.872931.

  5. Diazotrophy in alluvial meadows of subarctic river systems.

    Directory of Open Access Journals (Sweden)

    Thomas H DeLuca

    Full Text Available There is currently limited understanding of the contribution of biological N2 fixation (diazotrophy to the N budget of large river systems. This natural source of N in boreal river systems may partially explain the sustained productivity of river floodplains in Northern Europe where winter fodder was harvested for centuries without fertilizer amendments. In much of the world, anthropogenic pollution and river regulation have nearly eliminated opportunities to study natural processes that shaped early nutrient dynamics of large river systems; however, pristine conditions in northern Fennoscandia allow for the retrospective evaluation of key biochemical processes of historical significance. We investigated biological N2 fixation (diazotrophy as a potential source of nitrogen fertility at 71 independent floodplain sites along 10 rivers and conducted seasonal and intensive analyses at a subset of these sites. Biological N2 fixation occurred in all floodplains, averaged 24.5 kg N ha(-1 yr(-1 and was down regulated from over 60 kg N ha(-1 yr(-1 to 0 kg N ha(-1 yr(-1 by river N pollution. A diversity of N2-fixing cyanobacteria was found to colonize surface detritus in the floodplains. The data provide evidence for N2 fixation to be a fundamental source of new N that may have sustained fertility at alluvial sites along subarctic rivers. Such data may have implications for the interpretation of ancient agricultural development and the design of contemporary low-input agroecosystems.

  6. Radioecology of tritiated water in subarctic soils and vegetation

    International Nuclear Information System (INIS)

    Salonen, L.; Miettinen, J.K.

    1982-01-01

    The residence times of tritium in various types of soils and plants have been determined in southern and northern Finland. The experiments were conducted in forest and agricultural environments where tritiated water was applied to the soil surface in the form of a single fall of rain. After that the movement and loss of tritiated water from the unsaturated zone was followed over a 2-4-year period in some forest areas. Uptake and loss of tritium in the tissue-free water and organic compounds of some native plants was studied in each area. The results indicated that in the subarctic area the half-residence times of tritium in soils and plants were greatly dependent on the climatic conditions at the time of the labelling and during the short growing seasons and also on the rate of water movement in the soil. In the experiments started during the best growing season the half-residence times in soil and plants do not differ from those determined in more temperate latitudes. (author)

  7. Lagrangian study of transport of subarctic water across the Subpolar Front in the Japan Sea

    Science.gov (United States)

    Prants, Sergey V.; Uleysky, Michael Yu.; Budyansky, Maxim V.

    2018-05-01

    The southward near-surface transport of transformed subarctic water across the Subpolar Front in the Japan Sea is simulated and analyzed based on altimeter data from January 1, 1993 to December 31, 2017. Computing Lagrangian indicators for a large number of synthetic particles, advected by the AVISO velocity field, we find preferred transport pathways across the Subpolar Front. The southward transport occurs mainly in the central part of the frontal zone due to suitable dispositions of mesoscale eddies promoting propagation of subarctic water to the south. It is documented with the help of Lagrangian origin and L-maps and verified by the tracks of available drifters. The transport of transformed subarctic water to the south is compared with the transport of transformed subtropical water to the north simulated by Prants et al. (Nonlinear Process Geophys 24(1):89-99, 2017c).

  8. An ecological paradox: high species diversity and low position of the upper forest line in the Andean Depression.

    Science.gov (United States)

    Peters, Thorsten; Braeuning, Achim; Muenchow, Jannes; Richter, Michael

    2014-06-01

    Systematic investigations of the upper forest line (UFL) primarily concentrate on mid and high latitudes of the Northern Hemisphere, whereas studies of Neotropical UFLs are still fragmentary. This article outlines the extraordinary high tree diversity at the UFL within the Andean Depression and unravels the links between the comparatively low position of the local UFL, high tree-species diversity, and climate. On the basis of Gentry's rapid inventory methodology for the tropics, vegetation sampling was conducted at 12 UFL sites, and local climate (temperature, wind, precipitation, and soil moisture) was investigated at six sites. Monotypic forests dominated by Polylepis were only found at the higher located margins of the Andean Depression while the lower situated core areas were characterized by a species-rich forest, which lacked the elsewhere dominant tree-species Polylepis. In total, a remarkably high tree-species number of 255 tree species of 40 different plant families was found. Beta-diversity was also high with more than two complete species turnovers. A non-linear relationship between the floristic similarity of the investigated study sites and elevation was detected. Temperatures at the investigated study sites clearly exceeded 5.5°C, the postulated threshold value for the upper tree growth limit in the tropics. Instead, quasi-permanent trade winds, high precipitation amounts, and high soil water contents affect the local position of the UFL in a negative way. Interestingly, most of the above-mentioned factors are also contributing to the high species richness. The result is a combination of a clearly marked upper forest line depression combined with an extraordinary forest line complexity, which was an almost unknown paradox.

  9. Spatial Patterns of Species Diversity and Phylogenetic Structure of Plant Communities in the Tianshan Mountains, Arid Central Asia

    Directory of Open Access Journals (Sweden)

    Hong-Xiang Zhang

    2017-12-01

    Full Text Available The Tianshan Mountains, located in arid Central Asia, have a humid climate and are biodiversity hotspots. Here, we aimed to clarify whether the pattern of species diversity and the phylogenetic structure of plant communities is affected by environmental variables and glacial refugia. In this study, plant community assemblies of 17 research sites with a total of 35 sample plots were investigated at the grassland/woodland boundaries on the Tianshan Mountains. Community phylogeny of these plant communities was constructed based on two plant DNA barcode regions. The indices of phylogenetic diversity and phylogenetic community structure were calculated for these sample plots. We first estimated the correlation coefficients between species richness (SR and environmental variables as well as the presence of glacial refugia. We then mapped the significant values of indices of community phylogeny (PD, RPD, NRI, and NTI to investigate the correlation between community phylogeny and environmental structure or macrozones in the study area. The results showed that a significantly higher value of SR was obtained for the refugial groups than for the colonizing groups (P < 0.05; presence of refugia and environmental variables were highly correlated to the pattern of variation in SR. Indices of community phylogeny were not significantly different between refugial and colonizing regions. Comparison with the humid western part showed that plant communities in the arid eastern part of the Tianshan Mountains tended to display more significant phylogenetic overdispersion. The variation tendency of the PhyloSor index showed that the increase in macro-geographical and environmental distance did not influence obvious phylogenetic dissimilarities between different sample plots. In conclusion, glacial refugia and environmental factors profoundly influenced the pattern of SR, but community phylogenetic structure was not affected by glacial refugia among different plant

  10. Insights into species diversity of associated crustose coralline algae (Corallinophycidae, Rhodophyta with Atlantic European maerl beds using DNA barcoding

    Directory of Open Access Journals (Sweden)

    Cristina Pardo

    2017-10-01

    Full Text Available DNA barcoding in combination with morpho-anatomical analysis was applied to study the diversity of crustose coralline algae associated to two maerl beds from two protected Atlantic European areas from Brittany and Galicia —France and Spain, respectively—. Given the records of gametophytes of the maerl species Phymatolithon calcareum under crustose growth-forms, and that associated crustose coralline algae appear to be involved in the recruitment of new maerl plants, we compared the species composition between the associated crustose coralline algae to Breton and Galician maerl beds with the maerl species identified in these beds in previous DNA barcoding surveys. Our molecular results revealed higher species diversity in associated crustose coralline algae than in maerl-forming species. Nine taxa of crustose coralline algae were found in both study areas: four in Brittany and five in Galicia. Three species from Brittany were identified as Phymatolithon calcareum, Phymatolithon lamii, and Lithophyllum hibernicum. The remaining six ones were assigned to the genera Phymatolithon and Mesophyllum, along with Lithothamnion and Lithophyllum. Morpho-anatomical examination of diagnostic characters corroborated our molecular identification. Our results showed that the most representative genus of crustose coralline algae in Brittany was Phymatolithon, while in Galicia was Mesophyllum. In Brittany, Phymatolithon calcareum was found under both growth-forms, maerl and crustose coralline algae, the latter assigned to the gametophyte stage by the presence of uniporate conceptacles. The recruitment of new maerl plants involving associated crustose coralline algae with maerl beds may occur, but only we can affirm it for Phymatolithon calcareum in Brittany. By contrast, the different species composition between both growth-forms in the Galician maerl beds would indicate that the fragmentation of own free-living maerl species appears to be the most common

  11. Phylogenetic and population genetic analyses of diploid Leucaena (Leguminosae; Mimosoideae) reveal cryptic species diversity and patterns of divergent allopatric speciation.

    Science.gov (United States)

    Govindarajulu, Rajanikanth; Hughes, Colin E; Bailey, C Donovan

    2011-12-01

    Leucaena comprises 17 diploid species, five tetraploid species, and a complex series of hybrids whose evolutionary histories have been influenced by human seed translocation, cultivation, and subsequent spontaneous hybridization. Here we investigated patterns of evolutionary divergence among diploid Leucaena through comprehensively sampled multilocus phylogenetic and population genetic approaches to address species delimitation, interspecific relationships, hybridization, and the predominant mode of speciation among diploids. Parsimony- and maximum-likelihood-based phylogenetic approaches were applied to 59 accessions sequenced for six SCAR-based nuclear loci, nrDNA ITS, and four cpDNA regions. Population genetic comparisons included 1215 AFLP loci representing 42 populations and 424 individuals. Phylogenetic results provided a well-resolved hypothesis of divergent species relationships, recovering previously recognized clades of diploids as well as newly resolved relationships. Phylogenetic and population genetic assessments identified two cryptic species that are consistent with geography and morphology. Findings from this study highlight the importance and utility of multilocus data in the recovery of complex evolutionary histories. The results are consistent with allopatric divergence representing the predominant mode of speciation among diploid Leucaena. These findings contrast with the potential hybrid origin of several tetraploid species and highlight the importance of human translocation of seed to the origin of these tetraploids. The recognition of one previously unrecognized species (L. cruziana) and the elevation of another taxon (L. collinsii subsp. zacapana) to specific status (L. zacapana) is consistent with a growing number of newly diagnosed species from neotropical seasonally dry forests, suggesting these communities harbor greater species diversity than previously recognized.

  12. Candida species diversity and antifungal susceptibility patterns in oral samples of HIV/AIDS patients in Baja California, Mexico.

    Science.gov (United States)

    Clark-Ordóñez, Isadora; Callejas-Negrete, Olga A; Aréchiga-Carvajal, Elva T; Mouriño-Pérez, Rosa R

    2017-04-01

    Candidiasis is the most common opportunistic fungal infection in HIV patients. The aims of this study were to identify the prevalence of carriers of Candida, Candida species diversity, and in vitro susceptibility to antifungal drugs. In 297 HIV/AIDS patients in Baja California, Mexico, Candida strains were identified by molecular methods (PCR-RFLP) from isolates of oral rinses of patients in Tijuana, Mexicali, and Ensenada. 56.3% of patients were colonized or infected with Candida. In Tijuana, there was a significantly higher percentage of carriers (75.5%). Out of the 181 strains that were isolated, 71.8% were Candida albicans and 28.2% were non-albicans species. The most common non-albicans species was Candida tropicalis (12.2%), followed by Candida glabrata (8.3%), Candida parapsilosis (2.2%), Candida krusei (1.7%), and Candida guilliermondii (1.1%). Candida dubliniensis was not isolated. Two associated species were found in 11 patients. In Mexicali and Ensenada, there was a lower proportion of Candida carriers compared to other regions in Mexico and worldwide, however, in Tijuana, a border town with many peculiarities, a higher carrier rate was found. In this population, only a high viral load was associated with oral Candida carriers. Other factors such as gender, use of antiretroviral therapy, CD4+ T-lymphocyte levels, time since diagnosis, and alcohol/ tobacco consumption, were not associated with Candida carriers. © The Author 2016. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Measuring species diversity in a subtropical forest across a tree size gradient: a comparison of diversity indices

    International Nuclear Information System (INIS)

    Ke, X.; Su, Z.; Hu, Y.; Zhou, Y.; Xu, M.

    2017-01-01

    Shannon-Wiener index and Simpson's diversity index together with other metrics, e.g., richness, number of stems per species or species-specific density (N: S ratio), and kurtosis, were applied to characterize the woody plant diversity patterns of a subtropical broadleaved forest in south China. The aims of our study were to compare the efficacy and sensitivity to community diversity measures between Shannon-Wiener index and Simpson's diversity index. Tree census data from a 5-ha sample plot was partitioned into 3 datasets by diameter class to represent 3 distinct woody plant communities for the characterization of diversity across communities. The 5-ha sample plot of the forest had a total abundance of 23,301 tree stems = 1 cm DBH and a richness of 139 species. The majority of tree stems were seedlings (41.1%) and saplings (38.8%), whereas canopy trees only accounted for 20.1% of the total tree stems. Both Shannon-Wiener index and Simpson's diversity index decreased significantly in response to a decrease in the N: S ratio across the datasets, but Shannon-Wiener index was more sensitive to plot-based richness changes and had a higher efficacy in predicting changes in species richness. Our findings are contrary to the general belief that Shannon-Wiener index is an insensitive measure of the character of the N: S relationship and have demonstrated that it remains a good measure for species diversity in plant community studies for its sensitivity and efficacy. We also suggest that the kurtosis statistic can be used as a new diversity measure due to its sensitivity to diversity change. (author)

  14. Aboveground Biomass and Carbon in a South African Mistbelt Forest and the Relationships with Tree Species Diversity and Forest Structures

    Directory of Open Access Journals (Sweden)

    Sylvanus Mensah

    2016-04-01

    Full Text Available Biomass and carbon stocks are key information criteria to understand the role of forests in regulating global climate. However, for a bio-rich continent like Africa, ground-based measurements for accurate estimation of carbon are scarce, and the variables affecting the forest carbon are not well understood. Here, we present the first biomass study conducted in South Africa Mistbelt forests. Using data from a non-destructive sampling of 59 trees of four species, we (1 evaluated the accuracy of multispecies aboveground biomass (AGB models, using predictors such as diameter at breast height (DBH, total height (H and wood density; (2 estimated the amount of biomass and carbon stored in the aboveground compartment of Mistbelt forests and (3 explored the variation of aboveground carbon (AGC in relation to tree species diversity and structural variables. We found significant effects of species on wood density and AGB. Among the candidate models, the model that incorporated DBH and H as a compound variable (DBH2 × H was the best fitting. AGB and AGC values were highly variable across all plots, with average values of 358.1 Mg·ha−1 and 179.0 Mg·C·ha−1, respectively. Few species contributed 80% of AGC stock, probably as a result of selection effect. Stand basal area, basal area of the ten most important species and basal area of the largest trees were the most influencing variables. Tree species richness was also positively correlated with AGC, but the basal area of smaller trees was not. These results enable insights into the role of biodiversity in maintaining carbon storage and the possibilities for sustainable strategies for timber harvesting without risk of significant biomass decline.

  15. Cross-scale analysis of the region effect on vascular plant species diversity in southern and northern European mountain ranges.

    Directory of Open Access Journals (Sweden)

    Jonathan Lenoir

    Full Text Available BACKGROUND: The divergent glacial histories of southern and northern Europe affect present-day species diversity at coarse-grained scales in these two regions, but do these effects also penetrate to the more fine-grained scales of local communities? METHODOLOGY/PRINCIPAL FINDINGS: We carried out a cross-scale analysis to address this question for vascular plants in two mountain regions, the Alps in southern Europe and the Scandes in northern Europe, using environmentally paired vegetation plots in the two regions (n = 403 in each region to quantify four diversity components: (i total number of species occurring in a region (total γ-diversity, (ii number of species that could occur in a target plot after environmental filtering (habitat-specific γ-diversity, (iii pair-wise species compositional turnover between plots (plot-to-plot β-diversity and (iv number of species present per plot (plot α-diversity. We found strong region effects on total γ-diversity, habitat-specific γ-diversity and plot-to-plot β-diversity, with a greater diversity in the Alps even towards distances smaller than 50 m between plots. In contrast, there was a slightly greater plot α-diversity in the Scandes, but with a tendency towards contrasting region effects on high and low soil-acidity plots. CONCLUSIONS/SIGNIFICANCE: We conclude that there are strong regional differences between coarse-grained (landscape- to regional-scale diversity components of the flora in the Alps and the Scandes mountain ranges, but that these differences do not necessarily penetrate to the finest-grained (plot-scale diversity component, at least not on acidic soils. Our findings are consistent with the contrasting regional Quaternary histories, but we also consider alternative explanatory models. Notably, ecological sorting and habitat connectivity may play a role in the unexpected limited or reversed region effect on plot α-diversity, and may also affect the larger-scale diversity

  16. Potentialities of line planting technique in rehabilitation of logged over area referred to species diversity, growth and soil quality

    Directory of Open Access Journals (Sweden)

    PRIJANTO PAMOENGKAS

    2010-01-01

    Full Text Available Pamoengkas P (2010 Potentialities of line planting technique in rehabilitation of logged over area referred to species diversity, growth and soil quality. Biodiversitas 11: 34-39. Human interventions in the utilization of tropical forest resources are experiencing unanticipated consequences. The selective logging practices generally cause considerable damage to vegetation and the soil surface. It is supposed that soil condition and vegetation growth rate are deteriorated and reduced. Therefore, scientist strongly argue that the only way to achieve sustainability of Indonesian natural forest will require that the production natural forest is managed through methods that are acceptable from the perspective of environment as well as timber production. This means that there will be a strong need and incentive for methods and innovative technology. For more than two decades, tropical rainforest in Indonesia have been managed intensively under the Indonesian selective cutting (TPI and later on by the Indonesian selective cutting and replanting (TPTI and then, selective cutting and line planting (TPTJ system. TPTJ, as one example of selective cutting, recently become a proper alternative should be taken into consideration in the management of production natural forest in Indonesia by planting dipterocarp species in line. In this system, planting line (width 3 m and intermediate line (width 17 m are made alternately. The initial width of line is 3 m and to be expanded until 10 m within 5 years to introduce more light. The objective of this research was to assess growth and soil quality of TPTJ system. The object of research was TPTJ plot of various ages from 1 year to 7 years. For achieving the objective, 14 sample plots measuring 200 m x 200 m each, were laid out at research plots. The result showed that growth respond of Shorea leprosula toward the width of planting line was better comparing to Shorea parvifolia, but generally from this growth

  17. Predicting species diversity of benthic communities within turbid nearshore using full-waveform bathymetric LiDAR and machine learners.

    Directory of Open Access Journals (Sweden)

    Antoine Collin

    Full Text Available Epi-macrobenthic species richness, abundance and composition are linked with type, assemblage and structural complexity of seabed habitat within coastal ecosystems. However, the evaluation of these habitats is highly hindered by limitations related to both waterborne surveys (slow acquisition, shallow water and low reactivity and water clarity (turbid for most coastal areas. Substratum type/diversity and bathymetric features were elucidated using a supervised method applied to airborne bathymetric LiDAR waveforms over Saint-Siméon-Bonaventure's nearshore area (Gulf of Saint-Lawrence, Québec, Canada. High-resolution underwater photographs were taken at three hundred stations across an 8-km(2 study area. Seven models based upon state-of-the-art machine learning techniques such as Naïve Bayes, Regression Tree, Classification Tree, C 4.5, Random Forest, Support Vector Machine, and CN2 learners were tested for predicting eight epi-macrobenthic species diversity metrics as a function of the class number. The Random Forest outperformed other models with a three-discretized Simpson index applied to epi-macrobenthic communities, explaining 69% (Classification Accuracy of its variability by mean bathymetry, time range and skewness derived from the LiDAR waveform. Corroborating marine ecological theory, areas with low Simpson epi-macrobenthic diversity responded to low water depths, high skewness and time range, whereas higher Simpson diversity relied upon deeper bottoms (correlated with stronger hydrodynamics and low skewness and time range. The degree of species heterogeneity was therefore positively linked with the degree of the structural complexity of the benthic cover. This work underpins that fully exploited bathymetric LiDAR (not only bathymetrically derived by-products, coupled with proficient machine learner, is able to rapidly predict habitat characteristics at a spatial resolution relevant to epi-macrobenthos diversity, ranging from clear to

  18. Importance of Triticosecale Wittmack ex A.Camus varieties in the formation of species diversity of agro-ecosystems

    Directory of Open Access Journals (Sweden)

    В. В. Москалець

    2015-12-01

    Full Text Available Purpose. To find out the ecological importance of winter triticale varieties in the formation of species diversity of agro-ecosystems. Methods. Field, laboratoryones and mathematical and statistical analysis. Results. The authors studied ecological importance of winter triticale varieties of forest-steppe and Polissia ecotopes as determinants of agrobiocenosis in the structural and functional organization of species diversity. It was found that less favourable ecological niche for pests-phytophags is such winter triticale varieties and lines as ‘Slavetne’, ‘AD 256’, ‘Chaian’, ‘DAU 5’, for epiphytoparasites – ‘Vivate Nosivske’, ‘Pshenychne’, ‘Slavetne polipshene’, ‘Slavetne’, ‘Yaguar’, respectively. It is determined that varieties and lines of winter triticale such as ‘AD 256’, ‘Vivate Nosivske’, ‘Pshenychne’, ‘Slavetne polipshene’, ‘Slavetne’ show high biological ability to compete with synanthropic vegetation and form distinct associations of segetal plants. Conclusions. It was found that agrophytocenoses of the studied varieties of winter triticale under the conditions of forest-steppe, Polissia-forest-steppe and Polissia ecotops determined in movements structural and functional organization of species diversity of agroecosystems.

  19. Tillage and straw management affect PM10 emission potential in subarctic Alaska

    Science.gov (United States)

    Emission of PM10 (particulates =10 um in diameter regulated by many nations as an air pollutant) from agricultural soils can impact regional air quality. Little information exists that describes the potential for PM10 and airborne dust emissions from subarctic soils or agricultural soils subject to ...

  20. Youth Environmental Science Outreach in the Mushkegowuk Territory of Subarctic Ontario, Canada

    Science.gov (United States)

    Karagatzides, Jim D.; Kozlovic, Daniel R.; De Iuliis, Gerry; Liberda, Eric N.; General, Zachariah; Liedtke, Jeff; McCarthy, Daniel D.; Gomez, Natalya; Metatawabin, Daniel; Tsuji, Leonard J. S.

    2011-01-01

    We connected youth of the Mushkegowuk Territory (specifically Fort Albany First Nation) with environmental science and technology mentors in an outreach program contextualized to subarctic Ontario that addressed some of the environmental concerns identified by members of Fort Albany First Nation. Most activities were community-based centering on…

  1. Bacterial community structure and soil properties of a subarctic tundra soil in Council, Alaska.

    Science.gov (United States)

    Kim, Hye Min; Jung, Ji Young; Yergeau, Etienne; Hwang, Chung Yeon; Hinzman, Larry; Nam, Sungjin; Hong, Soon Gyu; Kim, Ok-Sun; Chun, Jongsik; Lee, Yoo Kyung

    2014-08-01

    The subarctic region is highly responsive and vulnerable to climate change. Understanding the structure of subarctic soil microbial communities is essential for predicting the response of the subarctic soil environment to climate change. To determine the composition of the bacterial community and its relationship with soil properties, we investigated the bacterial community structure and properties of surface soil from the moist acidic tussock tundra in Council, Alaska. We collected 70 soil samples with 25-m intervals between sampling points from 0-10 cm to 10-20 cm depths. The bacterial community was analyzed by pyrosequencing of 16S rRNA genes, and the following soil properties were analyzed: soil moisture content (MC), pH, total carbon (TC), total nitrogen (TN), and inorganic nitrogen (NH4+ and NO3-). The community compositions of the two different depths showed that Alphaproteobacteria decreased with soil depth. Among the soil properties measured, soil pH was the most significant factor correlating with bacterial community in both upper and lower-layer soils. Bacterial community similarity based on jackknifed unweighted unifrac distance showed greater similarity across horizontal layers than through the vertical depth. This study showed that soil depth and pH were the most important soil properties determining bacterial community structure of the subarctic tundra soil in Council, Alaska. © 2014 The Authors. FEMS Microbiology Ecology published by John Wiley & Sons Ltd on behalf of the Federation of European Microbiological Societies.

  2. Wind-driven circulation in the subarctic north Pacific using altimeter ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    of the wind stress curl are also related to the variation of the subarctic gyre. Though the correlation .... mum in spring, accounting for 41% of all the vari- ance. This estimate ..... plays an important role as a western boundary and it is also located ...

  3. The Performance Of Alternative Interest Rate Risk Measures And Immunization Strategies Under A Heath-Jarrow-Morton Framework

    OpenAIRE

    Agca, Senay

    2002-01-01

    The Heath-Jarrow-Morton (HJM) model represents the latest in powerful arbitrage-free technology for modeling the term structure and managing interest rate risk. Yet risk management strategies in the form of immunization portfolios using duration, convexity, and M-square are still widely used in bond portfolio management today. This study addresses the question of how traditional risk measures and immunization strategies perform when the term structure evolves in the HJM manner. Using Monte Ca...

  4. Characteristics of summer-time energy exchange in a high Arctic tundra heath 2000–2010

    Directory of Open Access Journals (Sweden)

    Magnus Lund

    2014-07-01

    Full Text Available Global warming will bring about changes in surface energy balance of Arctic ecosystems, which will have implications for ecosystem structure and functioning, as well as for climate system feedback mechanisms. In this study, we present a unique, long-term (2000–2010 record of summer-time energy balance components (net radiation, R n; sensible heat flux, H; latent heat flux, LE; and soil heat flux, G from a high Arctic tundra heath in Zackenberg, Northeast Greenland. This area has been subjected to strong summer-time warming with increasing active layer depths (ALD during the last decades. We observe high energy partitioning into H, low partitioning into LE and high Bowen ratio (β=H/LE compared with other Arctic sites, associated with local climatic conditions dominated by onshore winds, slender vegetation with low transpiration activity and relatively dry soils. Surface saturation vapour pressure deficit (D s was found to be an important variable controlling within-year surface energy partitioning. Throughout the study period, we observe increasing H/R n and LE/R n and decreasing G/R n and β, related to increasing ALD and decreasing soil wetness. Thus, changes in summer-time surface energy balance partitioning in Arctic ecosystems may be of importance for the climate system.

  5. CLIMOOR. Climate driven changes in the functioning of heath and moorland ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Beier, C. [ed.; Tietema, A.; Riis Nielsen, T.; Emmett, B.; Estiarte, M.; Penuelas, J.; Llorens Guash, L.; Williams, D.; Gordon, C.; Pugh, B.; Roda, F.; Gundersen, P.; Gorissen, A.

    2000-01-01

    Emission of green house gases, partly generated from human activities, reduces the loss of heat from the earth thereby potentially causing climate change. This change in climate has been predicted to result in a 1-3 deg. C increase in temperature with more vigorous rainstorms and prolonged drought periods in the coming 100 years. The consequence of such climatic changes for the terrestrial ecosystems are largely unknown. In order to improve our understanding of the ecosystem response to climate change and thereby to improve the basis for the international negotiations and political decisions to avoid or minimise climate change and its effects, a European research project CLIMOOR has been initiated. The project is a cross European research project involving 6 research groups from Denmark, the Netherlands, UK and Spain and is funded by EU and the participating institutions. The project investigates the potential effects of warming and drought on heath and moorland ecosystems at four European sites. The ecosystems are manipulated at field scale by reducing the heat loss at night by IR-reflective curtains and by removing the precipitation during a 2 month period in the summer. The effects of these manipulations on the plants and the soil are studied. This report describes the technique used to apply the climate change at field scale and presents some preliminary results after the first growing season. EU and the participating institutions fund CLIMOOR. (au)

  6. A monitoring protocol for vegetation change on Irish peatland and heath

    Science.gov (United States)

    O'Connell, J.; Connolly, J.; Holden, N. M.

    2014-09-01

    Amendments to Articles 3.3 and 3.4 of the Kyoto Protocol have meant that detection of vegetation change may now form an interracial part of national soil carbon stocks. In this study multispectral multi-platform satellite data was processed to detect change to the surface vegetation of four peatland sites and one heath in Ireland. Spectral and spatial thresholds were used on difference images between master and slave data in the extraction of temporally invariant targets for multi-platform cross calibration. The Kolmogorov-Smirnov test was used to evaluate any difference in the cumulative probability distributions of the master, slave and calibrated slave data as expressed by the D statistic, with values reduced by an average of 89.7% due to the cross calibration procedure. A change detection model was created which incorporated a spatial threshold of 9 pixels and a standard deviation (SD) spectral threshold. Kappa accuracy values for the five sites ranged from 80 to 97%, showing that 1.5 SD was the optimum spectral threshold for detecting vegetation change. Change detection results showed mean percentage change ranging from 2.11 to 3.28% of total area and cumulative change over the observed time period of between 15.24 and 49.27% of total area.

  7. Growth responses of low-alpine dwarf-shrub heath species to nitrogen deposition and management

    International Nuclear Information System (INIS)

    Britton, Andrea J.; Fisher, Julia M.

    2008-01-01

    Nitrogen deposition is a continuing problem in European alpine regions. We hypothesised that, despite climatic limitations, low-alpine Calluna heathland would respond to nitrogen addition with increased shoot growth and flowering and that fire and grazing would modify responses. In a five-year study, 0-50 kg N ha -1 y -1 were added, combined with burning (+/-) and clipping (+/-). Calluna vulgaris responded with increased shoot extension, but effects on flowering were variable. Burning enhanced the positive effect of nitrogen addition and negative effects of clipping. Sub-dominant shrubs generally did not respond to nitrogen. C. vulgaris shoot extension was stimulated by nitrogen addition of 10 kg N ha -1 y -1 (above background) supporting suggestions that alpine heathlands are sensitive to low levels of nitrogen deposition. Increased C. vulgaris growth could negatively impact on important lichen components of this vegetation through increased shading and competition. Climatic factors constrain productivity in this community, but do not prevent rapid responses to nitrogen deposition by some species. - Low levels of N deposition increase productivity in alpine dwarf-shrub heath despite strong climatic constraints

  8. Quantifying Direct and Indirect Impact of Future Climate on Sub-Arctic Hydrology

    Science.gov (United States)

    Endalamaw, A. M.; Bolton, W. R.; Young-Robertson, J. M.; Morton, D.; Hinzman, L. D.

    2016-12-01

    Projected future climate will have a significant impact on the hydrology of interior Alaskan sub-arctic watersheds, directly though the changes in precipitation and temperature patterns, and indirectly through the cryospheric and ecological impacts. Although the latter is the dominant factor controlling the hydrological processes in the interior Alaska sub-arctic, it is often overlooked in many climate change impact studies. In this study, we aim to quantify and compare the direct and indirect impact of the projected future climate on the hydrology of the interior Alaskan sub-arctic watersheds. The Variable Infiltration Capacity (VIC) meso-scale hydrological model will be implemented to simulate the hydrological processes, including runoff, evapotranspiration, and soil moisture dynamics in the Chena River Basin (area = 5400km2), located in the interior Alaska sub-arctic region. Permafrost and vegetation distribution will be derived from the Geophysical Institute Permafrost Lab (GIPL) model and the Lund-Potsdam-Jena Dynamic Global Model (LPJ) model, respectively. All models will be calibrated and validated using historical data. The Scenario Network for Alaskan and Arctic Planning (SNAP) 5-model average projected climate data products will be used as forcing data for each of these models. The direct impact of climate change on hydrology is estimated using surface parameterization derived from the present day permafrost and vegetation distribution, and future climate forcing from SNAP projected climate data products. Along with the projected future climate, outputs of GIPL and LPJ will be incorporated into the VIC model to estimate the indirect and overall impact of future climate on the hydrology processes in the interior Alaskan sub-arctic watersheds. Finally, we will present the potential hydrological and ecological changes by the end of the 21st century.

  9. The Heath government and British defence policy in Southeast Asia at the end of empire (1970-71).

    Science.gov (United States)

    Andrea, Benvenuti

    2009-01-01

    This article examines the rationale behind the Heath government's 1970 decision to negotiate a Five Power Defence agreement with Australia, New Zealand, Singapore and Malaysia and to maintain a small British military contingent in Southeast Asia as a part of this new politico-military framework. It argues that while its overriding foreign policy concern was to end Britain's problematic relationship with the European Economic Community and to make membership of this grouping the cornerstone of its foreign policy, the Heath government was careful not to cast Britain's post-imperial future in purely European terms. The successful negotiation of the Five Power Defence Arrangements in 1970-71 was instrumental in achieving this by ensuring that London would maintain close links with key Commonwealth partners in the Asian region. In what was not only an attempt to neutralize potential domestic opposition to Britain's entry into the EEC, but also a lingering reluctance to do away with the rhetoric of Britain as a leading power with extra-European interests, Heath was eager to show that by making a contribution to the stability of Southeast Asia, Britain still had a role to play outside Europe.

  10. Assessing the recovery potential of alpine moss-sedge heath: Reciprocal transplants along a nitrogen deposition gradient

    Energy Technology Data Exchange (ETDEWEB)

    Armitage, Heather F., E-mail: h.armitage@abdn.ac.u [Macaulay Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom); Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 3UU (United Kingdom); Britton, Andrea J. [Macaulay Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom); Woodin, Sarah J. [Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 3UU (United Kingdom); Wal, Rene van der [Aberdeen Centre for Environmental Sustainability (ACES), School of Biological Sciences, University of Aberdeen, Aberdeen AB24 3UU (United Kingdom)

    2011-01-15

    The potential of alpine moss-sedge heath to recover from elevated nitrogen (N) deposition was assessed by transplanting Racomitrium lanuginosum shoots and vegetation turfs between 10 elevated N deposition sites (8.2-32.9 kg ha{sup -1} yr{sup -1}) and a low N deposition site, Ben Wyvis (7.2 kg ha{sup -1} yr{sup -1}). After two years, tissue N of Racomitrium shoots transplanted from higher N sites to Ben Wyvis only partially equilibrated to reduced N deposition whereas reciprocal transplants almost matched the tissue N of indigenous moss. Unexpectedly, moss shoot growth was stimulated at higher N deposition sites. However, moss depth and biomass increased in turfs transplanted to Ben Wyvis, apparently due to slower shoot turnover (suggested to result partly from decreased tissue C:N slowing decomposition), whilst abundance of vascular species declined. Racomitrium heath has the potential to recover from the impacts of N deposition; however, this is constrained by the persistence of enhanced moss tissue N contents. - Alpine moss-sedge heath, dominated by Racomitrium lanuginosum, from across the UK has the potential to recover from the impacts of N pollution; however, this is constrained by persistence of enhanced moss tissue N contents.

  11. Assessing the recovery potential of alpine moss-sedge heath: Reciprocal transplants along a nitrogen deposition gradient

    International Nuclear Information System (INIS)

    Armitage, Heather F.; Britton, Andrea J.; Woodin, Sarah J.; Wal, Rene van der

    2011-01-01

    The potential of alpine moss-sedge heath to recover from elevated nitrogen (N) deposition was assessed by transplanting Racomitrium lanuginosum shoots and vegetation turfs between 10 elevated N deposition sites (8.2-32.9 kg ha -1 yr -1 ) and a low N deposition site, Ben Wyvis (7.2 kg ha -1 yr -1 ). After two years, tissue N of Racomitrium shoots transplanted from higher N sites to Ben Wyvis only partially equilibrated to reduced N deposition whereas reciprocal transplants almost matched the tissue N of indigenous moss. Unexpectedly, moss shoot growth was stimulated at higher N deposition sites. However, moss depth and biomass increased in turfs transplanted to Ben Wyvis, apparently due to slower shoot turnover (suggested to result partly from decreased tissue C:N slowing decomposition), whilst abundance of vascular species declined. Racomitrium heath has the potential to recover from the impacts of N deposition; however, this is constrained by the persistence of enhanced moss tissue N contents. - Alpine moss-sedge heath, dominated by Racomitrium lanuginosum, from across the UK has the potential to recover from the impacts of N pollution; however, this is constrained by persistence of enhanced moss tissue N contents.

  12. Characterization of subarctic vegetation using ground based remote sensing methods

    Science.gov (United States)

    Finnell, D.; Garnello, A.; Palace, M. W.; Sullivan, F.; Herrick, C.; Anderson, S. M.; Crill, P. M.; Varner, R. K.

    2014-12-01

    Stordalen mire is located at 68°21'N and 19°02'E in the Swedish subarctic. Climate monitoring has revealed a warming trend spanning the past 150 years affecting the mires ability to hold stable palsa/hummock mounds. The micro-topography of the landscape has begun to degrade into thaw ponds changing the vegetation cover from ombrothrophic to minerotrophic. Hummocks are ecologically important due to their ability to act as a carbon sinks. Thaw ponds and sphagnum rich transitional zones have been documented as sources of atmospheric CH4. An objective of this project is to determine if a high resolution three band camera (RGB) and a RGNIR camera could detect differences in vegetation over five different site types. Species composition was collected for 50 plots with ten repetitions for each site type: palsa/hummock, tall shrub, semi-wet, tall graminoid, and wet. Sites were differentiated based on dominating species and features consisting of open water presence, sphagnum spp. cover, graminoid spp. cover, or the presence of dry raised plateaus/mounds. A pole based camera mount was used to collect images at a height of ~2.44m from the ground. The images were cropped in post-processing to fit a one-square meter quadrat. Texture analysis was performed on all images, including entropy, lacunarity, and angular second momentum. Preliminary results suggested that site type influences the number of species present. The p-values for the ability to predict site type using a t-test range from use of a stepwise regression of texture variables, actual vs. predicted percent of vegetation coverage provided R squared values of 0.73, 0.71, 0.67, and 0.89 for C. bigelowii, R. chamaemorus, Sphagnum spp., and open water respectively. These data have provided some support to the notion that texture analyses can be used for classification of mire site types. Future work will involve scaling up from the 50 plots through the use of data collected from two unmanned aerial systems (UAS), as

  13. Doubled volatile organic compound emissions from subarctic tundra under simulated climate warming

    DEFF Research Database (Denmark)

    Faubert, Patrick; Tiiva, Paivi; Rinnan, Åsmund

    2010-01-01

    heath hosting a long-term warming and mountain birch (Betula pubescens ssp. czerepanovii) litter addition experiment. • The relatively low emissions of monoterpenes and sesquiterpenes were doubled in response to an air temperature increment of only 1.9-2.5°C, while litter addition had a minor influence...

  14. On the use of mulching to mitigate permafrost thaw due to linear disturbances in sub-arctic peatlands

    Science.gov (United States)

    The presence or absence of permafrost significantly influences the hydrology and ecology of northern watersheds. Resource exploration activities are currently having noticeable effects on hydrological and ecological processes in sub-arctic peatlands. Disturbances such as seismic cutlines can result ...

  15. The Social Structure of Participants of the Battle of Blore Heath (September 23, 1459

    Directory of Open Access Journals (Sweden)

    Andrey G. Prazdnikov

    2017-03-01

    Full Text Available The battle of Blore Heath which took place on September 23, 1459, marked the new stage of the Wars of Roses, which led to the change of dynasties at the English throne in less than two years. As it was not the clash of the main forces of House of Lancaster and House of York, the sources contain poor information about the battle’s participants. However, the analysis different sources let identify the names of 22 participants. Prosopographic study of this group contributes to the study of social behavior models, the degree of influence of the Wars of Roses on English society, the activity of representatives of different social strata. The social structure of the group, most of which are the representatives of the English gentry, is the object of the article. There is information in the sources about the origin of the knights. The House of York under the command of Earl of Salisbury were mostly from Northern and North-Western counties (Yorkshire, Westmorland, whereas House of Lancaster formed their troops in Cheshire, Staffordshire and Lancashire. As a rule, officers in the army of the Earl of Salisbury, were in close personal or family ties with him. The study of further lives of the participants of the battle and biographies of their children showed that the adherence of the chosen dynasty was preserved by generations and change of the parties was rather a deviation from the norm. English nobility of the second half of the 15th century had a high opinion of the value of loyalty and honor.

  16. Carbon monoxide and methane in the North American Arctic and Subarctic troposphere - July-August 1988

    Energy Technology Data Exchange (ETDEWEB)

    Harriss, R.C.; Sachse, G.W.; Hill, G.F.; Wade, L.; Bartlett, K.B.; Collins, J.E.; Steele, L.P.; Novelli, P.C. (New Hampshire Univ., Durham (United States) NASA, Langley Research Center, Hampton, VA (United States) Lockheed Engineering Sciences Co., Hampton, VA (United States) Science and Technology Corp., Hampton, VA (United States) Cooperative Inst. for Research in Environmental Sciences, Boulder, CO (United States))

    1992-10-01

    Enhanced concentrations of CH4 in the unpolluted atmospheric mixed layer over both Arctic and subarctic tundra landscapes are documented here using data from the NASA Arctic Boundary Layer Expedition (ABLE 3A). The CH4 concentration gradients were determined mainly by interactions of biogenic emission from wet tundra and turbulent mixing proceses. The gradient were most frequently associated with intrusion of upper tropospheric or stratospheric air into the midtroposphere, emissions from forest and tundra fires, and long-range transport of enhanced concentration of these gases from unidentified sources. Summertime haze layers exhibited midtropospheric enhancements of CH4 similar to those measured in winter Arctic events. The observations confirm the importance of Arctic and Subarctic wetland environments as a regional source of global atmospheric CH4. 33 refs.

  17. Carbon monoxide and methane in the North American Arctic and Subarctic troposphere - July-August 1988

    Science.gov (United States)

    Harriss, Robert C.; Sachse, Glen W.; Hill, Gerald F.; Wade, Larry; Bartlett, Karen B.; Collins, James E.; Steele, L. P.; Novelli, Paul C.

    1992-01-01

    Enhanced concentrations of CH4 in the unpolluted atmospheric mixed layer over both Arctic and subarctic tundra landscapes are documented here using data from the NASA Arctic Boundary Layer Expedition (ABLE 3A). The CH4 concentration gradients were determined mainly by interactions of biogenic emission from wet tundra and turbulent mixing proceses. The gradient were most frequently associated with intrusion of upper tropospheric or stratospheric air into the midtroposphere, emissions from forest and tundra fires, and long-range transport of enhanced concentration of these gases from unidentified sources. Summertime haze layers exhibited midtropospheric enhancements of CH4 similar to those measured in winter Arctic events. The observations confirm the importance of Arctic and Subarctic wetland environments as a regional source of global atmospheric CH4.

  18. Diversity and population structure of Marine Group A bacteria in the Northeast subarctic Pacific Ocean

    OpenAIRE

    Allers, Elke; Wright, Jody J; Konwar, Kishori M; Howes, Charles G; Beneze, Erica; Hallam, Steven J; Sullivan, Matthew B

    2012-01-01

    Marine Group A (MGA) is a candidate phylum of Bacteria that is ubiquitous and abundant in the ocean. Despite being prevalent, the structural and functional properties of MGA populations remain poorly constrained. Here, we quantified MGA diversity and population structure in relation to nutrients and O2 concentrations in the oxygen minimum zone (OMZ) of the Northeast subarctic Pacific Ocean using a combination of catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) and ...

  19. Recent changes in aquatic biota in subarctic Fennoscandia - the role of global and local environmental variables

    Science.gov (United States)

    Weckström, Jan; Leppänen, Jaakko; Sorvari, Sanna; Kaukolehto, Marjut; Weckström, Kaarina; Korhola, Atte

    2013-04-01

    The Arctic, representing a fifth of the earth's surface, is highly sensitive to the predicted future warming and it has indeed been warming up faster than most other regions. This makes the region critically important and highlights the need to investigate the earliest signals of global warming and its impacts on the arctic and subarctic aquatic ecosystems and their biota. It has been demonstrated that many Arctic freshwater ecosystems have already experienced dramatic and unpreceded regime shifts during the last ca. 150 years, primarily driven by climate warming. However, despite the indisputable impact of climate-related variables on freshwater ecosystems other, especially local-scale catchment related variables (e.g. geology, vegetation, human activities) may override the climate signal and become the primary factor in shaping the structure of aquatic ecosystems. Although many studies have contributed to an improved understanding of limnological and hydrobiological features of Artic and subarctic lakes, much information is still needed especially on the interaction between the biotic and abiotic components, i.e. on factors controlling the food web dynamics in these sensitive aquatic ecosystems. This is of special importance as these lakes are of great value in water storage, flood prevention, and maintenance of biodiversity, in addition to which they are vital resources for settlement patterns, food production, recreation, and tourism. In this study we compare the pre-industrial sediment assemblages of primary producers (diatoms and Pediastrum) and primary consumers (cladoceran and chironomids) with their modern assemblages (a top-bottom approach) from 50 subarctic Fennoscandian lakes. We will evaluate the recent regional pattern of changes in aquatic assemblages, and assess how coherent the lakes' responses are across the subarctic area. Moreover, the impact of global (e.g. climate, precipitation) and local (e.g. lake and its catchment characteristics) scale

  20. Phylogenetic relationships and cryptic species diversity in the Brazilian egg-brooding tree frog, genus Fritziana Mello-Leitão 1937 (Anura: Hemiphractidae).

    Science.gov (United States)

    Walker, Marina; Lyra, Mariana L; Haddad, Célio F B

    2018-06-01

    The genus Fritziana (Anura: Hemiphractidae) comprises six described species (F. goeldii, F. ohausi, F. fissilis, F. ulei, F. tonimi, and F. izecksohni) that are endemic to the Brazilian Atlantic Forest. Although the genus has been the subject of studies dealing with its taxonomy, phylogeny, and systematics, there is considerable evidence for cryptic diversity hidden among the species. The present study aims to understand the genetic diversity and phylogenetic relationships among the species of Fritziana, as well as the relationships among populations within species. We analyzed 107 individuals throughout the distribution of the genus using three mitochondrial gene fragments (12S, 16S, and COI) and two nuclear genes (RAG1 and SLC8A3). Our data indicated that the species diversity in the genus Fritziana is underestimated by the existence of at least three candidate species hidden amongst the group of species with a closed dorsal pouch (i.e. F. fissilis and F. ulei). We also found four species presenting geographical population structures and high genetic diversity, and thus require further investigations. In addition, we found that two candidate species show a new arrangement for the tRNA-Phe gene, unique in Anura so far. Based on our results, we suggest that the conservation status of the species, as well as the species diversity in the genus Fritziana, needs to be reviewed. Copyright © 2018 Elsevier Inc. All rights reserved.

  1. The influence of gap size on plant species diversity and composition in beech (Fagus orientalis forests, Ramsar, Mazandaran Province, North of Iran

    Directory of Open Access Journals (Sweden)

    MARZIEH BEGYOM-FAGHIR

    2013-10-01

    Full Text Available Pourbabaei H, Haddadi-Moghaddam H, Begyom-Faghir M, Abedi T. 2013. The influence of gap size on plant species diversity and composition in beech (Fagus orientalis forests, Ramsar, Mazandaran Province, North of Iran. Biodiversitas 14: 89-94.This study was conducted to investigate the influence of gap size on plant species diversity and composition in beech (Fagus orientalis Lipsky. forests, Ramsar, Mazandaran province. Fifteen gaps in small, medium, and large sizes were randomly selected. Abundance of tree saplings, shrubs and herbaceous species were counted on 4 m2 micro-plots within the gaps. Diversity indices including Shannon-Wiener, Simpson, Mc Arthur's N1, Hill's N2, species richness and Smith-Wilson’s evenness index were computed. The results revealed that there was significant difference among three gap categories in terms of diversity. The highest diversity values of tree and herbaceous species were obtained in the large gaps, while the highest diversity value of shrub species was in the medium gaps. Species composition of small gaps (28 species: 7 trees and 21 herbaceous, medium gaps (37 species: 7 trees, 5 shrubs and 25 herbaceous and large gaps (40 species: 7 trees, 4 shrubs and 29 herbaceous were recognized. Therefore, based on the results of this study, it is recommended that in order to maintain plant diversity and composition up to 400 m2 gap size cloud be used in this forests.

  2. Is Tree Species Diversity or Species Identity the More Important Driver of Soil Carbon Stocks, C/N Ratio, and pH?

    DEFF Research Database (Denmark)

    Dawud, Seid Muhie; Raulund-Rasmussen, Karsten; Domisch, Timo

    2016-01-01

    We explored tree species diversity effects on soil C stock, C/N ratio, and pH as compared with effects of tree species identity. We sampled forest floors and mineral soil (0–40 cm) in a diversity gradient of 1–5 tree species composed of conifers and broadleaves in Białowieża Forest, Poland...... mechanism for higher root carbon input and in turn a deeper distribution of C in diverse forests. Diversity and identity affected soil pH in topsoil with positive and negative impacts, respectively. More diverse forests would lead to higher soil nutrient status as reflected by higher topsoil p......H, but there was a slight negative effect on N status as indicated by higher C/N ratios in the deeper layers. We conclude that tree species diversity increases soil C stocks and nutrient status to some extent, but tree species identity is a stronger driver of the studied soil properties, particularly in the topsoil....

  3. Allochthonous Carbon--a Major Driver of Bacterioplankton Production in the Subarctic Northern Baltic Sea.

    Science.gov (United States)

    Figueroa, D; Rowe, O F; Paczkowska, J; Legrand, C; Andersson, A

    2016-05-01

    Heterotrophic bacteria are, in many aquatic systems, reliant on autochthonous organic carbon as their energy source. One exception is low-productive humic lakes, where allochthonous dissolved organic matter (ADOM) is the major driver. We hypothesized that bacterial production (BP) is similarly regulated in subarctic estuaries that receive large amounts of riverine material. BP and potential explanatory factors were measured during May-August 2011 in the subarctic Råne Estuary, northern Sweden. The highest BP was observed in spring, concomitant with the spring river-flush and the lowest rates occurred during summer when primary production (PP) peaked. PLS correlations showed that ∼60% of the BP variation was explained by different ADOM components, measured as humic substances, dissolved organic carbon (DOC) and coloured dissolved organic matter (CDOM). On average, BP was threefold higher than PP. The bioavailability of allochthonous dissolved organic carbon (ADOC) exhibited large spatial and temporal variation; however, the average value was low, ∼2%. Bioassay analysis showed that BP in the near-shore area was potentially carbon limited early in the season, while BP at seaward stations was more commonly limited by nitrogen-phosphorus. Nevertheless, the bioassay indicated that ADOC could contribute significantly to the in situ BP, ∼60%. We conclude that ADOM is a regulator of BP in the studied estuary. Thus, projected climate-induced increases in river discharge suggest that BP will increase in subarctic coastal areas during the coming century.

  4. Estimation of permafrost thawing rates in a sub-arctic catchment using recession flow analysis

    Directory of Open Access Journals (Sweden)

    S. W. Lyon

    2009-05-01

    Full Text Available Permafrost thawing is likely to change the flow pathways taken by water as it moves through arctic and sub-arctic landscapes. The location and distribution of these pathways directly influence the carbon and other biogeochemical cycling in northern latitude catchments. While permafrost thawing due to climate change has been observed in the arctic and sub-arctic, direct observations of permafrost depth are difficult to perform at scales larger than a local scale. Using recession flow analysis, it may be possible to detect and estimate the rate of permafrost thawing based on a long-term streamflow record. We demonstrate the application of this approach to the sub-arctic Abiskojokken catchment in northern Sweden. Based on recession flow analysis, we estimate that permafrost in this catchment may be thawing at an average rate of about 0.9 cm/yr during the past 90 years. This estimated thawing rate is consistent with direct observations of permafrost thawing rates, ranging from 0.7 to 1.3 cm/yr over the past 30 years in the region.

  5. Aircraft-measured indirect cloud effects from biomass burning smoke in the Arctic and subarctic

    Directory of Open Access Journals (Sweden)

    L. M. Zamora

    2016-01-01

    Full Text Available The incidence of wildfires in the Arctic and subarctic is increasing; in boreal North America, for example, the burned area is expected to increase by 200–300 % over the next 50–100 years, which previous studies suggest could have a large effect on cloud microphysics, lifetime, albedo, and precipitation. However, the interactions between smoke particles and clouds remain poorly quantified due to confounding meteorological influences and remote sensing limitations. Here, we use data from several aircraft campaigns in the Arctic and subarctic to explore cloud microphysics in liquid-phase clouds influenced by biomass burning. Median cloud droplet radii in smoky clouds were  ∼  40–60 % smaller than in background clouds. Based on the relationship between cloud droplet number (Nliq and various biomass burning tracers (BBt across the multi-campaign data set, we calculated the magnitude of subarctic and Arctic smoke aerosol–cloud interactions (ACIs, where ACI  =  (1∕3 × dln(Nliq∕dln(BBt to be  ∼  0.16 out of a maximum possible value of 0.33 that would be obtained if all aerosols were to nucleate cloud droplets. Interestingly, in a separate subarctic case study with low liquid water content ( ∼  0.02 g m−3 and very high aerosol concentrations (2000–3000 cm−3 in the most polluted clouds, the estimated ACI value was only 0.05. In this case, competition for water vapor by the high concentration of cloud condensation nuclei (CCN strongly limited the formation of droplets and reduced the cloud albedo effect, which highlights the importance of cloud feedbacks across scales. Using our calculated ACI values, we estimate that the smoke-driven cloud albedo effect may decrease local summertime short-wave radiative flux by between 2 and 4 W m−2 or more under some low and homogeneous cloud cover conditions in the subarctic, although the changes should be smaller in high surface albedo regions of the

  6. A “Rosetta Stone” for metazoan zooplankton: DNA barcode analysis of species diversity of the Sargasso Sea (Northwest Atlantic Ocean)

    Science.gov (United States)

    Bucklin, Ann; Ortman, Brian D.; Jennings, Robert M.; Nigro, Lisa M.; Sweetman, Christopher J.; Copley, Nancy J.; Sutton, Tracey; Wiebe, Peter H.

    2010-12-01

    Species diversity of the metazoan holozooplankton assemblage of the Sargasso Sea, Northwest Atlantic Ocean, was examined through coordinated morphological taxonomic identification of species and DNA sequencing of a ˜650 base-pair region of mitochondrial cytochrome oxidase I (mtCOI) as a DNA barcode (i.e., short sequence for species recognition and discrimination). Zooplankton collections were made from the surface to 5,000 meters during April, 2006 on the R/V R.H. Brown. Samples were examined by a ship-board team of morphological taxonomists; DNA barcoding was carried out in both ship-board and land-based DNA sequencing laboratories. DNA barcodes were determined for a total of 297 individuals of 175 holozooplankton species in four phyla, including: Cnidaria (Hydromedusae, 4 species; Siphonophora, 47); Arthropoda (Amphipoda, 10; Copepoda, 34; Decapoda, 9; Euphausiacea, 10; Mysidacea, 1; Ostracoda, 27); and Mollusca (Cephalopoda, 8; Heteropoda, 6; Pteropoda, 15); and Chaetognatha (4). Thirty species of fish (Teleostei) were also barcoded. For all seven zooplankton groups for which sufficient data were available, Kimura-2-Parameter genetic distances were significantly lower between individuals of the same species (mean=0.0114; S.D. 0.0117) than between individuals of different species within the same group (mean=0.3166; S.D. 0.0378). This difference, known as the barcode gap, ensures that mtCOI sequences are reliable characters for species identification for the oceanic holozooplankton assemblage. In addition, DNA barcodes allow recognition of new or undescribed species, reveal cryptic species within known taxa, and inform phylogeographic and population genetic studies of geographic variation. The growing database of "gold standard" DNA barcodes serves as a Rosetta Stone for marine zooplankton, providing the key for decoding species diversity by linking species names, morphology, and DNA sequence variation. In light of the pivotal position of zooplankton in ocean

  7. Monoterpene emissions in response to long-term night-time warming, elevated CO2 and extended summer drought in a temperate heath ecosystem

    DEFF Research Database (Denmark)

    Tiiva, Päivi; Tang, Jing; Michelsen, Anders

    2017-01-01

    Monoterpenes emitted from plants have an important role in atmospheric chemistry through changing atmospheric oxidative capacity, forming new particles and secondary organic aerosols. The emission rates and patterns can be affected by changing climate. In this study, emission responses to six years...... of climatic manipulations (elevated CO2, extended summer drought and night-time warming) were investigated in a temperate semi-natural heath ecosystem. Samples for monoterpene analysis were collected in seven campaigns during an entire growing season (April-November, 2011). The results showed...... that the temperate heath ecosystem was a considerable source of monoterpenes to the atmosphere, with the emission averaged over the 8month measurement period of 21.7±6.8μgm(-2)groundareah(-1) for the untreated heath. Altogether, 16 monoterpenes were detected, of which the most abundant were α-pinene, δ-3-carene...

  8. Functional significance of tree species diversity and species identity on soil organic carbon, C/N ratio and pH in major European forest types

    DEFF Research Database (Denmark)

    Dawud, Seid Muhie

    Forests provide different ecosystem functions and services including soil carbon sequestration and nutrient supply to maintain growth and productivity. This PhD thesis explored tree species diversity and tree species identity (conifer proportion of basal area) effects on soil C stock and nutrient...... 8 and 12 years old common garden stands established in two contrasting bioclimatic regions. In all the studied contexts, tree species identity (confers versus broadleaves) was stronger than diversity in consistently driving variability of the examined soil properties and root characteristics......, particularly in topsoil layers. Diversity did not affect fine root characteristics of the young forests and effects on soil properties were different under the investigated contexts. Across the different European sites, diversity had no effect on C/N ratio and pH but under comparable environmental conditions...

  9. Effects of species diversity on seasonal variation in herbage yield and nutritive value of seven binary grass-legume mixtures and pure grass under cutting

    DEFF Research Database (Denmark)

    Elgersma, Anjo; Søegaard, Karen

    2016-01-01

    Intensively managed sown temperate grasslands are generally of low species diversity, although swards based on grass-legume mixtures may have superior productivity and herbage quality than grass-only swards. We conducted a cutting experiment over two years to test the effect of species composition...... and diversity on herbage yield, contents of N, neutral detergent fibre (NDF) and in vitro organic matter digestibility (IVOMD). Perennial ryegrass (PR, Lolium perenne) was sown alone and with each of four forage legumes: red clover (RC, Trifolium pratense), lucerne (LU, Medicago sativa), birdsfoot trefoil (BT......, Lotus corniculatus) and white clover (WC, Trifolium repens); WC was also sown with hybrid ryegrass (HR, Lolium × boucheanum), meadow fescue (MF, Festuca pratensis) and timothy (TI, Phleum pratense). Herbage productivity was lowest in pure PR followed by PR/BT, and highest in PR/RC; this mixture had...

  10. How hedge woody species diversity and habitat change is a function of land use history and recent management in a European agricultural landscape.

    Science.gov (United States)

    McCann, Thomas; Cooper, Alan; Rogers, David; McKenzie, Paul; McErlean, Thomas

    2017-07-01

    European hedged agricultural landscapes provide a range of ecosystem services and are an important component of cultural and biodiversity heritage. This paper investigates the extent of hedges, their woody species diversity (including the influence of historical versus recent hedge origin) and dynamics of change. The rationale is to contribute to an ecological basis for hedge habitat management. Sample sites were allocated based on a multivariate classification of landscape attributes. All field boundaries present in each site were mapped and surveyed in 1998 and 2007. To assess diversity, a list of all woody species was recorded in one standard 30 m linear plot within each hedge. There was a net decrease in hedge habitat extent, mainly as a result of removal, and changes between hedges and other field boundary types due to the development and loss of shrub growth-form. Agricultural intensification, increased rural building, and variation in hedge management practices were the main drivers of change. Hedges surveyed at baseline, which were lost at resurvey, were more species rich than new hedges gained. Hedges coinciding with historical land unit boundaries of likely Early Medieval origin were found to be more species rich. The most frequent woody species in hedges were native, including a high proportion with Fraxinus excelsior, a species under threat from current and emerging plant pests and pathogens. Introduced species were present in circa 30% of hedges. We conclude that since hedge habitat distribution and woody species diversity is a function of ecology and anthropogenic factors, the management of hedges in enclosed agricultural landscapes requires an integrated approach. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Unexpected high species diversity among European stalked puffballs – a contribution to the phylogeny and taxonomy of the genus Tulostoma (Agaricales

    Directory of Open Access Journals (Sweden)

    Mikael Jeppson

    2017-04-01

    Full Text Available A three-gene data set was generated to explore species diversity and delimitations within the stalked puffballs (Tulostoma, Agaricales in Europe. Data on species from other parts of the world were included for comparison of species concepts and distribution ranges. Sequence data from 26 type specimens are included. The phylogenetic analyses support Tulostoma as monophyletic. Eleven major clades, 37 minor clades, and 20 single branches were recovered and found to correspond to 30 described species and 27 species without scientific names. Five species are here described as new to science: Tulostoma calcareum, T. calongei, T. eckbladii, T. grandisporum, and T. pannonicum. In total we report 26 described, and 19 undescribed, species from Europe. An epitype for T. fimbriatum with ITS sequence data is selected to fix the name. The recovered tree topology was not in congruence with the current infrageneric classification of Tulostoma, suggesting that many of the morphological characters used for segregation of taxa are plesiomorphic or homoplasious. Spore ornamentation and hyphal structure of the peridium are found to be reliable characters for delimitation of species. The majority of the species occur in the dry, arid areas of southern and east central Europe but a few are shown to be restricted to humid temperate regions in the North. The study confirms that species with smooth or sub-smooth spores are restricted to dry and arid habitats whereas species with more strongly ornamented spores occur in humid habitats. Areas with steppe vegetation in Hungary and Spain are here identified as hot spots for Tulostoma species diversity.

  12. Species diversity and metabolic impact of the microbiota are low in spontaneously acidified Belgian sausages with an added starter culture of Staphylococcus carnosus.

    Science.gov (United States)

    Janssens, M; Myter, N; De Vuyst, L; Leroy, F

    2012-04-01

    Quality of fermented sausages is affected by acidifying lactic acid bacteria (LAB) and colour- and flavour-promoting coagulase-negative staphylococci (CNS), whether or not used as starter culture. Artisan fermented sausages are often perceived as superior to industrial variants, partially because of the specific microbiota due to spontaneous acidification, which may be considered as an artisan characteristic. Therefore, two kinds of spontaneously acidified Belgian sausages were prepared (Belgian-type salami and Boulogne sausage), but with addition of a Staphylococcus carnosus culture. The Belgian-type salami was made from pork and beef, whereas the Boulogne sausage contained pork and horse meat. In all cases, Lactobacillus sakei was the dominant LAB species present on the raw materials and during fermentation, whereas enterococci remained present in the background. Enterobacteriaceae vanished after fermentation. The CNS species diversity on the raw materials was large and differed between the pork, beef, and horse meat. Nevertheless, this species diversity was annihilated during fermentation by the added S. carnosus culture. The volatiles fraction was mainly composed of aldehydes that originated from lipid oxidation and spices-derived compounds. Aromatic compounds that are typically associated to CNS activity, such as end-products from the metabolism of branched-chain amino acids, were not present in the Belgian-type salami and only marginally present in the Boulogne sausage. In conclusion, spontaneous acidification of Belgian-type fermented sausages leads to dominance of L. sakei and is no guarantee for bacterial contribution to the aroma profile when S. carnosus is added as a starter culture. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Three-spined stickleback Gasterosteus aculeatus, as a possible paratenic host for salmonid nematodes in a subarctic lake.

    Science.gov (United States)

    Braicovich, Paola E; Kuhn, Jesper A; Amundsen, Per-Arne; Marcogliese, David J

    2016-03-01

    In Takvatn, a subarctic lake in northern Norway, 35 of 162 three-spined sticklebacks examined were infected with 106 specimens of third-stage larvae of Philonema oncorhynchi. The prevalence and mean intensity of P. oncorhynchi were 10 % and 2.0 in 2013 and 24 % and 3.0 in 2014, respectively. A single specimen of Cystidicola farionis was found in an additional sample. While the latter is considered an accidental infection, three-spined sticklebacks may function as paratenic hosts of P. oncorhynchi, potentially enhancing its transmission to salmonids due to their central role in the lacustrine food web of this subarctic lake.

  14. Fog reduces transpiration in tree species of the Canarian relict heath-laurel cloud forest (Garajonay National Park, Spain).

    Science.gov (United States)

    Ritter, Axel; Regalado, Carlos M; Aschan, Guido

    2009-04-01

    The ecophysiologic role of fog in the evergreen heath-laurel 'laurisilva' cloud forests of the Canary Islands has not been unequivocally demonstrated, although it is generally assumed that fog water is important for the survival and the distribution of this relict paleoecosystem of the North Atlantic Macaronesian archipelagos. To determine the role of fog in this ecosystem, we combined direct transpiration measurements of heath-laurel tree species, obtained with Granier's heat dissipation probes, with micrometeorological and artificial fog collection measurements carried out in a 43.7-ha watershed located in the Garajonay National Park (La Gomera, Canary Islands, Spain) over a 10-month period. Median ambient temperature spanned from 7 to 15 degrees C under foggy conditions whereas higher values, ranging from 9 to 21 degrees C, were registered during fog-free periods. Additionally, during the periods when fog water was collected, global solar radiation values were linearly related (r2=0.831) to those under fog-free conditions, such that there was a 75+/-1% reduction in median radiation in response to fog. Fog events greatly reduced median diurnal tree transpiration, with rates about 30 times lower than that during fog-free conditions and approximating the nighttime rates in both species studied (the needle-like leaf Erica arborea L. and the broadleaf Myrica faya Ait.). This large decrease in transpiration in response to fog was independent of the time of the day, tree size and species and micrometeorological status, both when expressed on a median basis and in cumulative terms for the entire 10-month measuring period. We conclude that, in contrast to the turbulent deposition of fog water droplets on the heath-laurel species, which may be regarded as a localized hydrological phenomenon that is important for high-altitude wind-exposed E. arborea trees, the cooler, wetter and shaded microenvironment provided by the cloud immersion belt represents a large-scale effect

  15. Conceptualising the interactive effects of climate change and biological invasions on subarctic freshwater fish.

    Science.gov (United States)

    Rolls, Robert J; Hayden, Brian; Kahilainen, Kimmo K

    2017-06-01

    Climate change and species invasions represent key threats to global biodiversity. Subarctic freshwaters are sentinels for understanding both stressors because the effects of climate change are disproportionately strong at high latitudes and invasion of temperate species is prevalent. Here, we summarize the environmental effects of climate change and illustrate the ecological responses of freshwater fishes to these effects, spanning individual, population, community and ecosystem levels. Climate change is modifying hydrological cycles across atmospheric, terrestrial and aquatic components of subarctic ecosystems, causing increases in ambient water temperature and nutrient availability. These changes affect the individual behavior, habitat use, growth and metabolism, alter population spawning and recruitment dynamics, leading to changes in species abundance and distribution, modify food web structure, trophic interactions and energy flow within communities and change the sources, quantity and quality of energy and nutrients in ecosystems. Increases in temperature and its variability in aquatic environments underpin many ecological responses; however, altered hydrological regimes, increasing nutrient inputs and shortened ice cover are also important drivers of climate change effects and likely contribute to context-dependent responses. Species invasions are a complex aspect of the ecology of climate change because the phenomena of invasion are both an effect and a driver of the ecological consequences of climate change. Using subarctic freshwaters as an example, we illustrate how climate change can alter three distinct aspects of species invasions: (1) the vulnerability of ecosystems to be invaded, (2) the potential for species to spread and invade new habitats, and (3) the subsequent ecological effects of invaders. We identify three fundamental knowledge gaps focused on the need to determine (1) how environmental and landscape characteristics influence the

  16. Geographic Distribution of Ammonia-Oxidizing Archaea along the Kuril Islands in the Western Subarctic Pacific

    Directory of Open Access Journals (Sweden)

    Hongmei Jing

    2017-06-01

    Full Text Available Community composition and abundance of ammonia-oxidizing archaea (AOA in the ocean were affected by different physicochemical conditions, but their responses to physical barriers (such as a chain of islands were largely unknown. In our study, geographic distribution of the AOA from the surface photic zone to the deep bathypelagic waters in the western subarctic Pacific adjacent to the Kuril Islands was investigated using pyrosequencing based on the ammonia monooxygenase subunit A (amoA gene. Genotypes of clusters A and B dominated in the upper euphotic zone and the deep waters, respectively. Quantitative PCR assays revealed that the occurrence and ammonia-oxidizing activity of ammonia-oxidizing archaea (AOA reached their maxima at the depth of 200 m, where a higher diversity and abundance of actively transcribed AOA was observed at the station located in the marginal sea exposed to more terrestrial input. Similar community composition of AOA observed at the two stations adjacent to the Kuril Islands maybe due to water exchange across the Bussol Strait. They distinct from the station located in the western subarctic gyre, where sub-cluster WCAII had a specific distribution in the surface water, and this sub-cluster seemed having a confined distribution in the western Pacific. Habitat-specific groupings of different WCB sub-clusters were observed reflecting the isolated microevolution existed in cluster WCB. The effect of the Kuril Islands on the phylogenetic composition of AOA between the Sea of Okhotsk and the western subarctic Pacific is not obvious, possibly because our sampling stations are near to the Bussol Strait, the main gateway through which water is exchanged between the Sea of Okhotsk and the Pacific. The vertical and horizontal distribution patterns of AOA communities among stations along the Kuril Islands were essentially determined by the in situ prevailing physicochemical gradients along the two dimensions.

  17. Tolerance of an expanding subarctic shrub, Betula glandulosa, to simulated caribou browsing.

    Directory of Open Access Journals (Sweden)

    Emilie Champagne

    Full Text Available Densification of the shrub layer has been reported in many subarctic regions, raising questions about the implication for large herbivores and their resources. Shrubs can tolerate browsing and their level of tolerance could be affected by browsing and soils productivity, eventually modifying resource availability for the caribou. Our objective was to assess the compensatory growth potential of a subarctic shrub, Betula glandulosa Michx., in relation with caribou browsing and nutriment availability for the plants. We used a simulated browsing (0, 25 and 75% of available shoots and nitrogen-fertilisation (0 and 10 g m(-2 experiment to test two main hypotheses linking tolerance to resource availability, the Compensatory Continuum Hypothesis and the Growth Rate Hypothesis as well as the predictions from the Limiting Resource Model. We seek to explicitly integrate the relative browsing pressure in our predictions since the amount of tissues removed could affect the capacity of long-lived plants to compensate. Birches fully compensated for moderate browsing with an overall leaf biomass similar to unbrowsed birches but undercompensated under heavy browsing pressure. The main mechanism explaining compensation appears to be the conversion of short shoots into long shoots. The leaf area increased under heavy browsing pressure but only led to undercompensation. Fertilisation for two consecutive years did not influence the response of birch, thus we conclude that our results support the LRM hypothesis of equal tolerance under both high and low nitrogen availability. Our results highlight that the potential for compensatory growth in dwarf birch is surpassed under heavy browsing pressure independently of the fertilisation regime. In the context of the worldwide decline in caribou herds, the reduction in browsing pressure could act synergistically with global climate change to promote the current shrub expansion reported in subarctic regions.

  18. [BIODIVERSITY OF ACANTHOCEPHALANS (ACANTHOCEPHALA) IN FRESHWATER FISHES OF ASIATIC SUB-ARCTIC REGION].

    Science.gov (United States)

    Atrashkevich, G I; Mikhailova, E I; Orlovskaya, O M; Pospekhov, V V

    2016-01-01

    The analysis of taxonomical and ecological diversity of acanthocephalans in fishes of Asiatic sub-Arctic region freshwaters, summarizing changes in modern views on species composition, life cycles, and ecology of background groups of these parasites is given. A priority role of studies provided by O. N. Bauer and his scientific school in organization and development of these aspects of acanthocephalology is demonstrated. Special attention is paid to the assessment of acanthocephalan biodiversity of the genus Neoechinorhynchus, the background group of freshwater fish parasites of the Asiatic sub-Arctic region, and an original key for their species is given. The distribution of acanthocephalans of the genus Acanthocephalus in northeastern Asia is analyzed and prospective study of this parasite group, evolutionary associated with freshwater isopods of the genus Asellus as intermediate hosts, is outlined. The absence of documented evidences on intermediate hosts of other background parasites of freshwater fishes in the region, acanthocephalans of the genus Metechinorhynchus, is revealed. It is assumed that subsequent taxonomic revisions based both on morphological and molecular genetic studies are necessary for the reliable revealing of species composition in each genus of the background acanthocephalans from freshwater fishes of Northern Asia. Theoretical significance of the study of acanthocephalan life cycles and revealing their natural intermediate hosts for the reliable estimation of structural and functional organization of their host-parasite systems in different parts of the range is substantiated and the possibility of the distribution of taxonomic conclusions in new territories is analyzed. A brief annotated taxonomical list of freshwater acanthocephalans of the Asiatic sub-Arctic region is given.

  19. A mesoscale iron enrichment in the western subarctic Pacific induces a large centric diatom bloom.

    Science.gov (United States)

    Tsuda, Atsushi; Takeda, Shigenobu; Saito, Hiroaki; Nishioka, Jun; Nojiri, Yukihiro; Kudo, Isao; Kiyosawa, Hiroshi; Shiomoto, Akihiro; Imai, Keiri; Ono, Tsuneo; Shimamoto, Akifumi; Tsumune, Daisuke; Yoshimura, Takeshi; Aono, Tatsuo; Hinuma, Akira; Kinugasa, Masatoshi; Suzuki, Koji; Sohrin, Yoshiki; Noiri, Yoshifumi; Tani, Heihachiro; Deguchi, Yuji; Tsurushima, Nobuo; Ogawa, Hiroshi; Fukami, Kimio; Kuma, Kenshi; Saino, Toshiro

    2003-05-09

    We have performed an in situ test of the iron limitation hypothesis in the subarctic North Pacific Ocean. A single enrichment of dissolved iron caused a large increase in phytoplankton standing stock and decreases in macronutrients and dissolved carbon dioxide. The dominant phytoplankton species shifted after the iron addition from pennate diatoms to a centric diatom, Chaetoceros debilis, that showed a very high growth rate, 2.6 doublings per day. We conclude that the bioavailability of iron regulates the magnitude of the phytoplankton biomass and the key phytoplankton species that determine the biogeochemical sensitivity to iron supply of high-nitrate, low-chlorophyll waters.

  20. Does water stress, nutrient limitation, or H-toxicity explain the differential stature among Heath Forest types in Central Kalimantan, Indonesia?

    NARCIS (Netherlands)

    Vernimmen, R.R.E.; Bruijnzeel, L.A.; Proctor, J.; Verhoef, H.A.; Klomp, N.

    2013-01-01

    To investigate the causes of the reduced stature of heath forest compared to lowland evergreen rain forest (LERF), the quantity and quality of small litterfall (LF), the standing crop of litter on the forest floor (LSC), and the annual rates of litter decay were determined over a period of 12 months

  1. A catchment-scale carbon and greenhouse gas budget of a subarctic landscape

    DEFF Research Database (Denmark)

    Christensen, Torben R; Johansson, Torbjörn; Olsrud, Maria

    2007-01-01

    forest, and mires, lakes and alpine ecosystems. The magnitudes of atmospheric exchange of carbon in the form of the GHGs, CO2 and CH4 in these various ecosystems differ significantly, ranging from little or no flux in barren ecosystems over a small CO2 sink function and low rates of CH4 exchange...... in the heaths to significant CO2 uptake in the forests and also large emissions of CH4 from the mires and small lakes. The overall catchment budget, given the size distribution of the individual ecosystem types and a first approximation of run-off as dissolved organic carbon, reveals a landscape currently...

  2. Building on Sub-Arctic Soil: Geopolymerization of Muskeg to a Densified Load-Bearing Composite.

    Science.gov (United States)

    Waetzig, Gregory R; Cho, Junsang; Lacroix, Max; Banerjee, Sarbajit

    2017-11-07

    The marshy water-saturated soil typical of the sub-Arctic represents a considerable impediment to the construction of roads, thereby greatly hindering human habitation and geological excavation. Muskeg, the native water-laden topsoil characteristic of the North American sub-Arctic, represents a particularly vexing challenge for road construction. Muskeg must either be entirely excavated, or for direct construction on muskeg, a mix of partial excavation and gradual compaction with the strategic placement of filling materials must be performed. Here, we demonstrate a novel and entirely reversible geopolymerization method for reinforcing muskeg with wood fibers derived from native vegetation with the addition of inorganic silicate precursors and without the addition of extraneous metal precursors. A continuous siloxane network is formed that links together the muskeg, wood fibers, and added silicates yielding a load-bearing and low-subsidence composite. The geopolymerization approach developed here, based on catalyzed formation of a siloxane network with further incorporation of cellulose, allows for an increase of density as well as compressive strength while reducing the compressibility of the composite.

  3. Alien roadside species more easily invade alpine than lowland plant communities in a subarctic mountain ecosystem.

    Directory of Open Access Journals (Sweden)

    Jonas J Lembrechts

    Full Text Available Effects of roads on plant communities are not well known in cold-climate mountain ecosystems, where road building and development are expected to increase in future decades. Knowledge of the sensitivity of mountain plant communities to disturbance by roads is however important for future conservation purposes. We investigate the effects of roads on species richness and composition, including the plant strategies that are most affected, along three elevational gradients in a subarctic mountain ecosystem. We also examine whether mountain roads promote the introduction and invasion of alien plant species from the lowlands to the alpine zone. Observations of plant community composition were made together with abiotic, biotic and anthropogenic factors in 60 T-shaped transects. Alpine plant communities reacted differently to road disturbances than their lowland counterparts. On high elevations, the roadside species composition was more similar to that of the local natural communities. Less competitive and ruderal species were present at high compared with lower elevation roadsides. While the effects of roads thus seem to be mitigated in the alpine environment for plant species in general, mountain plant communities are more invasible than lowland communities. More precisely, relatively more alien species present in the roadside were found to invade into the surrounding natural community at high compared to low elevations. We conclude that effects of roads and introduction of alien species in lowlands cannot simply be extrapolated to the alpine and subarctic environment.

  4. Alien roadside species more easily invade alpine than lowland plant communities in a subarctic mountain ecosystem.

    Science.gov (United States)

    Lembrechts, Jonas J; Milbau, Ann; Nijs, Ivan

    2014-01-01

    Effects of roads on plant communities are not well known in cold-climate mountain ecosystems, where road building and development are expected to increase in future decades. Knowledge of the sensitivity of mountain plant communities to disturbance by roads is however important for future conservation purposes. We investigate the effects of roads on species richness and composition, including the plant strategies that are most affected, along three elevational gradients in a subarctic mountain ecosystem. We also examine whether mountain roads promote the introduction and invasion of alien plant species from the lowlands to the alpine zone. Observations of plant community composition were made together with abiotic, biotic and anthropogenic factors in 60 T-shaped transects. Alpine plant communities reacted differently to road disturbances than their lowland counterparts. On high elevations, the roadside species composition was more similar to that of the local natural communities. Less competitive and ruderal species were present at high compared with lower elevation roadsides. While the effects of roads thus seem to be mitigated in the alpine environment for plant species in general, mountain plant communities are more invasible than lowland communities. More precisely, relatively more alien species present in the roadside were found to invade into the surrounding natural community at high compared to low elevations. We conclude that effects of roads and introduction of alien species in lowlands cannot simply be extrapolated to the alpine and subarctic environment.

  5. Wintertime phytoplankton bloom in the Subarctic Pacific supported by continental margin iron

    International Nuclear Information System (INIS)

    Lam, Phoebe J.; Bishop, James K.B.; Henning, Cara C.; Marcus, Matthew A.; Waychunas, Glenn A.; Fung, Inez

    2004-01-01

    Heightened biological activity was observed in February 1996 in the high-nutrient low-chlorophyll (HNLC) subarctic North Pacific Ocean, a region that is thought to be iron-limited. Here we provide evidence supporting the hypothesis that Ocean Station Papa (OSP) in the subarctic Pacific received a lateral supply of particulate iron from the continental margin off the Aleutian Islands in the winter, coincident with the observed biological bloom. Synchrotron X-ray analysis was used to describe the physical form, chemistry, and depth distributions of iron in size fractionated particulate matter samples. The analysis reveals that discrete micron-sized iron-rich hotspots are ubiquitous in the upper 200m at OSP, more than 900km from the closest coast. The specifics of the chemistry and depth profiles of the Fe hot spots trace them to the continental margins. We thus hypothesize that iron hotspots are a marker for the delivery of iron from the continental margin. We confirm the delivery of continental margin iron to the open ocean using an ocean general circulation model with an iron-like tracer source at the continental margin. We suggest that iron from the continental margin stimulated a wintertime phytoplankton bloom, partially relieving the HNLC condition

  6. The transformation and fate of sub-Arctic microphytobenthos carbon revealed through 13C-labeling

    DEFF Research Database (Denmark)

    Oakes, Joanne M.; Rysgaard, Søren; Glud, Ronnie N.

    2016-01-01

    Microphytobenthos (MPB) at higher latitudes has been poorly studied. This study used pulse-chase C-13-labeling to investigate the production, processing, and fate of MPB-derived carbon (MPB-C) in sub-Arctic intertidal sediments over 31 d. Gross primary production (2.1 mmolCm(-2)h(-1)+/- 0.4 mmol...... accounted for49.8% of this C-13. The C-13 content of sediment organic carbon declined over time, but>31% of the C-13 fixed within the first tidal cycle remained after 31 d, suggesting that sub-Arctic MPB may contribute to coastal carbon retention during the productive season. Over 21 d, 10.6% of the fixed C......-13 was removed via DIC fluxes and 0.3% via DOC fluxes from inundated sediment, and 0.6% as CO2 from exposed sediment. The greatest loss of C-13 (38.2%) was via unmeasured pathways, including resuspension and/or removal by mobile consumers. The rates of MPB-C production and the relative importance...

  7. Evidences of Seasonal Variation in Altimetry Derived Ocean Tides in the Subarctic Ocean

    Directory of Open Access Journals (Sweden)

    Hok Sum Fok

    2013-01-01

    Full Text Available While the barotropic ocean tides in the deep ocean are well modeled to ~2 cm RMS, accurate tidal prediction in the ice-covered polar oceans and near coastal regions remain elusive. A notable reason is that the most accurate satellite altimeters (TOPEX/Jason-1/-2, whose orbits are optimized to minimize the tidal aliasing effect, have spatial coverage limited to largely outside of the polar ocean. Here, we update the assessment of tidal models using 7 contemporary global and regional models, and show that the altimetry sea surface height (SSH anomaly residual after tidal correction is 9 - 12 cm RMS in the Subarctic Ocean. We then address the hypothesis whether plausible evidence of variable tidal signals exist in the seasonally ice-covered Subarctic Ocean, where the sea ice cover is undergoing rapid thinning. We first found a difference in variance reduction for multi-mission altimeter SSH anomaly residuals during the summer and winter seasons, with the residual during winter season 15 - 30% larger than that during the summer season. Experimental seasonal ocean tide solutions derived from satellite altimetry reveals that the recovered winter and summer tidal constituents generally differ by a few cm in amplitude and tens of degrees in phase. Relatively larger seasonal tidal patterns, in particular for M2, S2 and K1 tides, have been identified in the Chukchi Sea study region near eastern Siberia, coincident with the seasonal presence and movement of sea ice.

  8. Analysis of anaerobic BTX biodegradation in a subarctic aquifer using isotopes and benzylsuccinates.

    Science.gov (United States)

    McKelvie, Jennifer R; Lindstrom, Jon E; Beller, Harry R; Richmond, Sharon A; Sherwood Lollar, Barbara

    2005-12-01

    In situ biodegradation of benzene, toluene, and xylenes in a petroleum hydrocarbon contaminated aquifer near Fairbanks, Alaska was assessed using carbon and hydrogen compound specific isotope analysis (CSIA) of benzene and toluene and analysis of signature metabolites for toluene (benzylsuccinate) and xylenes (methylbenzylsuccinates). Carbon and hydrogen isotope ratios of benzene were between -25.9 per thousand and -26.8 per thousand for delta13C and -119 per thousand and -136 per thousand for delta2H, suggesting that biodegradation of benzene is unlikely at this site. However, biodegradation of both xylenes and toluene were documented in this subarctic aquifer. Biodegradation of xylenes was indicated by the presence of methylbenzylsuccinates with concentrations of 17-50 microg/L in three wells. Anaerobic toluene biodegradation was also indicated by benzylsuccinate concentrations of 10-49 microg/L in the three wells with the highest toluene concentrations (1500-5000 microg/L toluene). Since benzylsuccinate typically accounts for a very small fraction of the toluene present in groundwater (generally data is particularly valuable given the challenge of verifying biodegradation in subarctic environments where degradation rates are typically much slower than in temperate environments.

  9. The importance of colony structure versus shoot morphology for the water balance of 22 subarctic bryophyte species

    NARCIS (Netherlands)

    Elumeeva, Tatiana G.; Soudzilovskaia, Nadejda A.; During, Heinjo J.; Cornelissen, Johannes H.C.

    Questions: What are the water economy strategies of the dominant subarctic bryophytes in terms of colony and shoot traits? Can colony water retention capacity be predicted from morphological traits of both colonies and separate shoots? Are suites of water retention traits consistently related to

  10. Experimentally increased nutrient availability at the permafrost thaw front selectively enhances biomass production of deep-rooting subarctic peatland species

    NARCIS (Netherlands)

    Keuper, Frida; Dorrepaal, Ellen; van Bodegom, Peter M.; van Logtestijn, Richard; Venhuizen, Gemma; van Hal, Jurgen; Aerts, Rien

    2017-01-01

    Climate warming increases nitrogen (N) mineralization in superficial soil layers (the dominant rooting zone) of subarctic peatlands. Thawing and subsequent mineralization of permafrost increases plant-available N around the thaw-front. Because plant production in these peatlands is N-limited, such

  11. Sub-arctic hydrology and climate change : a case study of the Tana River Basin in Northern Fennoscandia

    NARCIS (Netherlands)

    Dankers, Rutger

    2002-01-01

    The most significant changes in climate, due to the well-known enhanced greenhouse effect, are generally expected to occur at northern high latitudes. Sub-arctic environments, that are dominated by the presence of a seasonal snow cover, may therefore be particularly sensitive to global warming. The

  12. Influence of Afforestation on the Species Diversity of the Soil Seed Bank and Understory Vegetation in the Hill-Gullied Loess Plateau, China.

    Science.gov (United States)

    Wang, Ning; Jiao, Juying; Jia, Yanfeng; Wang, Dongli

    2017-10-24

    The Chinese Loess Plateau region has long been suffering from serious soil erosion. Thus, large-scale afforestation has continued during the past decades in order to control soil erosion. Afforestation can dramatically alter nutrient cycles, affect soil-carbon storage, and change hydrology. However, it is unknown how afforestation influences species diversity of the soil seed bank and understory vegetation compared with spontaneous restoration of abandoned land. Forest land with trees planted 30 years ago, abandoned slope land restored spontaneously for 30 years, and the corresponding slopes with remnant natural vegetation were selected as sampling sites. The species richness both in the soil seed bank and vegetation was significantly higher on the afforested slope compared to the spontaneously restored abandoned land. The species similarity between the afforested slope and the remnant slope land was high both in the soil seed bank and standing vegetation compared to the abandoned land. The soil seed bank density varied from 1778 ± 187 to 3896 ± 221 seeds/m², and more than half of it was constituted by annual and biennial species, with no significant difference among sampling habitats. However, the afforested slope had higher seed density of grass and shrub/subshrubs compared to the abandoned slope. The present study indicates that in the study region, characterized by serious soil erosion, afforestation can better facilitate vegetation succession compared to spontaneously restoration of abandoned slope land.

  13. The genus Atheris (Serpentes: Viperidae) in East Africa: phylogeny and the role of rifting and climate in shaping the current pattern of species diversity.

    Science.gov (United States)

    Menegon, M; Loader, S P; Marsden, S J; Branch, W R; Davenport, T R B; Ursenbacher, S

    2014-10-01

    Past climatic and tectonic events are believed to have strongly influenced species diversity in the Eastern Afromontane Biodiversity Hotspot. We investigated the phylogenetic relationships and historical biogeography of the East African genus Atheris (Serpentes: Viperidae), and explored temporal and spatial relationships between Atheris species across Africa, and the impact of palaeoclimatic fluctuations and tectonic movements on cladogenesis of the genus. Using mitochondrial sequence data, the phylogeny of East African species of Atheris shows congruent temporal patterns that link diversification to major tectonic and aridification events within East Africa over the last 15million years (my). Our results are consistent with a scenario of a delayed direct west-east colonisation of the Eastern Arc Mountains of Atheris by the formation of the western rift. Based on the phylogenetic patterns, this terrestrial, forest-associated genus has dispersed into East Africa across a divided route, on both west-southeasterly and west-northeasterly directions (a C-shaped route). Cladogenesis in the Eastern Arc Mountains and Southern Highlands of Tanzania corresponds to late Miocene and Plio-Pleistocene climatic shifts. Taxonomically, our data confirmed the monophyly of Atheris as currently defined, and reveal four major East African clades, three of which occur in discrete mountain ranges. Possible cryptic taxa are identified in the Atheris rungweensis and A. ceratophora clades. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Comparing the two Greek archipelagos plant species diversity and endemism patterns highlight the importance of isolation and precipitation as biodiversity drivers.

    Science.gov (United States)

    Iliadou, Eleni; Kallimanis, Athanasios S; Dimopoulos, Panayotis; Panitsa, Maria

    2014-12-01

    Greece has two island archipelagos, the Aegean and the Ionian, which host a rich array of plants and wildlife, particularly endemic and threatened plant species. Despite the long history of island biogeographic studies in the Aegean, similar studies in the Ionian remain limited, with the two island archipelagos rarely being compared. The Aegean and Ionian archipelagos share many features, especially regarding total plant diversity, but exhibit different patterns of endemism. For instance, when considering similarly sized islands, those in the Ionian host as many as, if not more, species compared to the Aegean. In contrast, the Ionian Islands are poor in endemics (particularly narrow range endemics, such as single island or regional endemics) and threatened taxa, compared to the Aegean Islands. In the Ionian, endemics only persist on the largest islands, and form a very small proportion of the species pool, compared to the Aegean archipelago. The lack of endemism might be attributed to the more recent separation of the Ionian Islands from the mainland and the shorter distance separating them from the mainland. In addition, the Ionian Islands receive higher levels of precipitation and are typically covered by denser and higher vegetation than the Aegean Islands. These conditions favour greater total species richness, but tend to lead to higher numbers of common species compared to threatened and endemic taxa. This study demonstrates that both isolation and precipitation serve as biodiversity drivers, influencing plant species diversity and endemism patterns, of the two Greek archipelagos.

  15. The use of genus-specific amplicon pyrosequencing to assess phytophthora species diversity using eDNA from soil and water in Northern Spain.

    Science.gov (United States)

    Català, Santiago; Pérez-Sierra, Ana; Abad-Campos, Paloma

    2015-01-01

    Phytophthora is one of the most important and aggressive plant pathogenic genera in agriculture and forestry. Early detection and identification of its pathways of infection and spread are of high importance to minimize the threat they pose to natural ecosystems. eDNA was extracted from soil and water from forests and plantations in the north of Spain. Phytophthora-specific primers were adapted for use in high-throughput Sequencing (HTS). Primers were tested in a control reaction containing eight Phytophthora species and applied to water and soil eDNA samples from northern Spain. Different score coverage threshold values were tested for optimal Phytophthora species separation in a custom-curated database and in the control reaction. Clustering at 99% was the optimal criteria to separate most of the Phytophthora species. Multiple Molecular Operational Taxonomic Units (MOTUs) corresponding to 36 distinct Phytophthora species were amplified in the environmental samples. Pyrosequencing of amplicons from soil samples revealed low Phytophthora diversity (13 species) in comparison with the 35 species detected in water samples. Thirteen of the MOTUs detected in rivers and streams showed no close match to sequences in international sequence databases, revealing that eDNA pyrosequencing is a useful strategy to assess Phytophthora species diversity in natural ecosystems.

  16. Influence of Afforestation on the Species Diversity of the Soil Seed Bank and Understory Vegetation in the Hill-Gullied Loess Plateau, China

    Science.gov (United States)

    Wang, Ning; Jiao, Juying; Jia, Yanfeng; Wang, Dongli

    2017-01-01

    The Chinese Loess Plateau region has long been suffering from serious soil erosion. Thus, large-scale afforestation has continued during the past decades in order to control soil erosion. Afforestation can dramatically alter nutrient cycles, affect soil-carbon storage, and change hydrology. However, it is unknown how afforestation influences species diversity of the soil seed bank and understory vegetation compared with spontaneous restoration of abandoned land. Forest land with trees planted 30 years ago, abandoned slope land restored spontaneously for 30 years, and the corresponding slopes with remnant natural vegetation were selected as sampling sites. The species richness both in the soil seed bank and vegetation was significantly higher on the afforested slope compared to the spontaneously restored abandoned land. The species similarity between the afforested slope and the remnant slope land was high both in the soil seed bank and standing vegetation compared to the abandoned land. The soil seed bank density varied from 1778 ± 187 to 3896 ± 221 seeds/m2, and more than half of it was constituted by annual and biennial species, with no significant difference among sampling habitats. However, the afforested slope had higher seed density of grass and shrub/subshrubs compared to the abandoned slope. The present study indicates that in the study region, characterized by serious soil erosion, afforestation can better facilitate vegetation succession compared to spontaneously restoration of abandoned slope land. PMID:29064405

  17. Effects of long-term warming and fertilisation on microarthropod abundances in three sub-arctic ecosystems

    DEFF Research Database (Denmark)

    Sjursen, Heidi; Michelsen, Anders; Jonasson, Sven Evert

    2005-01-01

    -5 years (glade), 11 years (fellfield), and 12 years (heath) at the time of sampling. In the glade soil, warming led to decreases in Collembola and Gamasida, and increases in Oribatida, although effects were inconsistent between years. Actinedida densities were increased by fertilization, while Acaridida...

  18. We adapt… but is it good or bad? Locating the political ecology and social-ecological systems debate in reindeer herding in the Swedish Sub-Arctic.

    NARCIS (Netherlands)

    Gallardo, Gloria; Saunders, Fred; Sokolova, Tatiana; Börebäck, Kristina; van Laerhoven, F.S.J.; Kokko, Suvi; Tuvendal, Magnus

    2017-01-01

    Abstract Reindeer herding (RDH) is a livelihood strategy deeply connected to Sami cultural tradition. This article explores the implications of two theoretical and methodological approaches for grasping complex socioenvironmental relationships of RDH in Subarctic Sweden. Based on joint fieldwork,

  19. Paleoproductivity and intermediate-water ventilation in the subarctic Northwest Pacific during the last deglaciation

    Science.gov (United States)

    Khim, B.; Ikehara, K.; Sagawa, T.; Shibahara, A.; Yamamoto, M.

    2010-12-01

    Laminated sediments during the last deglaciation in the subarctic North Pacific indicate significant depletion of dissolved oxygen concentration at intermediate water depths. Such a strong oxygen minimum zone results primarily from a combination of high surface water productivity and poor ventilation of intermediate waters. We investigated a variety of paleoclimatic proxies using about 8-m long piston core sediment (GH02-1030; 42o13.770N, 144o12.530E; water depth, 1212 m) obtained from the continental slope off Tokachi (eastern Hokkaido Island), which is the main path of the southwestward Oyashio Current in the subarctic Northwest Pacific. Laminated sediments were identified at the two horizons in the core GH02-1030; the upper one at 11.4-12.2 cal.kyr BP and the lower one at 14.1-14.7 cal.kyr BP, corresponding to Bølling-Allerød (B/A) and Preboreal (PB), respectively. Between these laminated layers, Younger Dryas occurred. Both laminated sediment layers are characterized by Bolivina tumida, B. pacifica, and Buliminella tenuata, indicating dysoxic bottom water conditions. Increased Mg/Ca-derived intermediate-water temperature and δ18OW values at B/A and PB periods suggest the poor ventilation of intermediate water because of the surface water freshening (i.e., decrease of surface-water salinity). UK'37-derived temperature record also supports the increase of surface-water temperature during B/A and PB intervals. During the last deglaciation, short-chain C14-C18 n-fatty acids, derived mainly from marine organisms, showed higher concentrations, indicating the increased surface-water production, and at the same time, abundant lignin reflected more contribution of terrigenous organic matter, supporting increased freshwater discharge. Variation of CaCO3 contents show remarkable double peaks, corresponding to B/A and PB periods, respectively, leading to the increase of TOC contents. Opal contents also follow similar pattern to CaCO3 contents, but are much less than the

  20. Carbon dioxide exchange in subarctic ecosystems measured by a micrometeorological technique

    International Nuclear Information System (INIS)

    Aurela, M.

    2005-01-01

    The atmospheric CO 2 concentration and the surface air temperatures have increased since the pre-industrial era, and the increase in both is predicted to continue during the 21st century. The feedback mechanisms between the changing climate and the carbon cycle are complex, and more information is needed about carbon exchange in different ecosystems. Northern Finland lies in the transition zone between boreal forest and tundra where the ecosystems are especially sensitive to any changes in the climate. In 1995-2004, micrometeorological eddy covariance measurements were conducted to yield continuous data on the CO 2 exchange between the atmosphere and the biosphere in northern Finland on four different ecosystems: an aapa mire, a mountain birch forest, a Scots pine forest and a Norway spruce forest. A measurement system enabling year-round measurements in the harsh subarctic conditions was developed and shown to be suitable for long-term exchange studies. A comparison of the CO 2 flux components, photosynthesis and respiration, at different ecosystems in the European subarctic and arctic regions showed that the leaf area index (LAI) is the key determinant of the gross photosynthetic rates, explaining greatest part of the variation between these ecosystems. Respiration did not show such a strong correlation with LAI, but in general, high respiration rates were related to high values of LAI. The first continuous round-the-year measurements of net ecosystem CO 2 exchange on a subarctic wetland were conducted at Kaamanen. The winter-time CO 2 efflux (of about 90 g CO 2 m -2 yr -1 ) was shown to constitute an essential part of the annual CO 2 balance (of -79 g CO 2 m -2 yr -1 in 1997-2002). The annual CO 2 balances at all sites in northern Finland were relatively small compared with those in lower latitudes. The interannual variation of the CO 2 balance at Kaamanen was marked (-15 to -195 g CO 2 m -2 yr -1 ) during the years 1997-2002. The most important factor

  1. Species diversity of greenbelt plant in Taiyuan urban%太原市城区绿地植物物种多样性研究

    Institute of Scientific and Technical Information of China (English)

    赵立曦; 陶莉; 张先平

    2012-01-01

    【Objective】 To provide a scientific basis for the planning and construction of the urban greenbelts and the protection and utilization of the plant diversity in the city of Taiyuan,the species diversity of Taiyuan city's greenbelt plants was investigated.【Method】 An investigation based on community ecology was adopted which focused on the types,factors and vertical stratification of green land in Taiyuan urban area;and the plant diversity of the greenbelt was assessed comprehensively in terms of the importance value index,diversity index,evenness index and Shannon-Wiener index.【Result】 The results show that on the green lands in Taiyuan urban area there are 83 families,243 genera and 402 species of vascular plants,which are mainly Rosaceae,Asteraceae,Leguminosae sp.,Salicaceae and so on;the exotic species are slightly more than the local ones and the hemerophyte species are highly more than the wild plants;the vertically distributed stratification of green land mainly includes the tree-shrubs and the shrub-herbs,of which the diversity index,evenness index and Shannon-Wiener index are all high.Besides,among green lands of different functions,Forest Garden,the Appertain green land,Longtan Garden and Yumen River Garden are of high Shannon-Wiener index and diversity index.【Conclusion】 The species diversity of greenbelt plants in Taiyuan city is just at an average level,therefore greater efforts must be put to increase and protect the plant diversity of the green lands in Taiyuan city.%【目的】调查太原市城区绿地植物物种的多样性,为太原市城市绿地的规划建设和植物物种多样性的保护与利用提供科学依据。【方法】采用群落生态学的调查方法,调查太原城区绿地植物的组成、构成要素及垂直结构等,运用重要值、丰富度指数、均匀度指数和Shannon-Wiener指数综合评价绿地植物的物种多样性。【结果】太原城区绿地共有维管束植物83科243属402

  2. Species diversity and distribution of freshwater crabs (Decapoda: Pseudothelphusidae inhabiting the basin of the Rio Grande de Térraba, Pacific slope of Costa Rica

    Directory of Open Access Journals (Sweden)

    Luis Rólier Lara

    2013-09-01

    Full Text Available During the last decades, knowledge on biodiversity of freshwater decapods has increased considerably; however, information about ecology of these crustaceans is scarce. Currently, the freshwater decapod fauna of Costa Rica is comprised by representatives of three families (Caridea: Palaemonidae and Atyidae; Brachyura: Pseudothelphusidae. The present study aims to describe the species diversity and distribution of freshwater crabs inhabiting the basin of the Rio Grande de Térraba, Pacific slope of Costa Rica, where the Instituto Costarricense de Electricidad (ICE plans to implement one of the largest damming projects in the region. Samples were collected in 39 locations at an altitude ranging from 20 to 1,225 m. Sampling was carried out during several months in 2007, 2009 and 2010. We collected a total of 661 crabs, comprising eight species of Pseudothelphusidae of three genera, representing 53% of the 15 pseudothelphusid crab species currently recorded from Costa Rica. The most common species was Ptychophallus paraxanthusi followed by P. tristani. Freshwater crabs were more frequently encountered in the middle-low region of the basin (between 311 and 600 m and less frequently in the medium-high basin (between 601 and 1,225 m. Ptychophallus paraxanthusi showed the widest distribution and was collected in altitudes ranging from 20 to 700 m. The Rio Grande de Térraba region can be considered as a relatively small, but highly diverse system. Therefore, any alteration of the basin of Rio Grande de Térraba, and especially the possible construction of a hydroelectric power plant, needs to be carefully analyzed to mitigate the damaging effects of this project on the freshwater crabs. More ecological information about freshwater crabs from Costa Rica and the Central American region are needed to reach a first reasonable overview on the ecological role of these decapods in freshwater systems.

  3. Recovery after 25 years of the tree and palms species diversity on a selectively logged forest in a Venezuelan lowland ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Lozada, J.R.; Arends, E.; Sánchez, D.; Villarreal, A.; Guevara, J.; Soriano, P.; Costa, M.

    2016-07-01

    Aim of the study: We evaluate palm and tree species diversity in a floodplain forest and the changes affecting the plots subjected to different intensities of selective logging. Area of study: The western alluvial plains of Venezuela. Materials and Methods: A randomized complete blocks design was established 25 years ago with three felling treatments (trees with diameter greater than 20 cm, 40 cm and 60 cm). Each treatment had three replications, using 1 ha permanent plots. We have measured all trees and palms bigger than over 10 cm in diameter. The data set was used to calculate the Importance Value Index of each species, the Shannon-Wiener index, the Hill Numbers and the Chao-Sørensen index. Main results: Disturbance increases the importance value index of pioneer species like Cecropia peltata, Ochroma pyramidale and Triplaris americana. All treatments produce changes on the floristic diversity but most of them are not significant. Only the high impact treatment causes a decrease in the species richness, but after 5 year of recovery this parameter is close to its previous levels (N0= 43.5). In logged forests, species loss (9.2%) is lower than in the control plots (11.7%) and is also lower than the rate of occurrence of species input (14.6%). Research highlights: In these logged forests restoration of diversity is acceptable because is higher than 91% (Chao-Sørensen index). Selective logging, with low and medium intensity, is a disturbance that works in a similar way to natural disturbances. All the diversity indexes recovered the pre-harvest level values. (Author)

  4. A molecular phylogeny of Afromontane dwarf geckos (Lygodactylus) reveals a single radiation and increased species diversity in a South African montane center of endemism.

    Science.gov (United States)

    Travers, Scott L; Jackman, Todd R; Bauer, Aaron M

    2014-11-01

    Afromontane habitats throughout eastern sub-Saharan Africa support remarkable levels of microendemism. However, despite being the subject of decades of research interest, biogeographical patterns of diversification throughout this disjunct montane system still remain largely unknown. We examined the evolutionary relationships of diurnal dwarf geckos (Lygodactylus) from several Afromontane regions throughout southeastern Africa, focusing primarily on two species groups (rex and bonsi groups). Using both mitochondrial and nuclear markers, we generate a molecular phylogeny containing all members of the rex and bonsi groups, to evaluate the monophyly of these groups along with previous biogeographic hypotheses suggesting independent southward invasions into the greater Drakensberg Afromontane center of endemism in northeastern South Africa by each group. Our results provide no support for these taxonomic and biogeographic hypotheses, and instead reveal geographically circumscribed patterns of diversification. One clade is restricted to the highlands of southern Malawi and northern Mozambique and the other to the greater Drakensberg region of northeastern South Africa and Swaziland. Interestingly, L. bernardi from the Nyanga Highlands of eastern Zimbabwe is nested within the primarily savanna-dwelling capensis group. We use Bayesian species delimitation methods to evaluate species limits within the greater Drakensberg clade, which support the elevation of the subspecies of L. ocellatus and L. nigropunctatus, thus bringing the total to eight species within a relatively confined geographic area. These results further highlight the greater Drakensberg Afromontane region as both an important center of endemism, as well as a center of diversification contributing to the accumulation of southern Africa's rich species diversity. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. Alternative technologies for remediation of technogenic barrens in the Kola Subarctic

    Science.gov (United States)

    Koptsik, G. N.; Koptsik, S. V.; Smirnova, I. E.

    2016-11-01

    The efficiency of remediation of technogenic barrens under the reduction of air pollutant emissions from the Severonikel smelter in the Kola Subarctic is determined largely by the soil state and the technology applied. The covering of the contaminated soils with artificially made material based on organomineral substrates and the following liming and fertilization promoted a sharp and long-term reduction of acidity, decrease in the biological availability of heavy metals, increase in the supply with nutrients, and improvement of the life state of willow and birch plantations. The effect of economically more profitable chemo-phytostabilization is short-term; it requires constant maintenance. Under the current production and a high level of soil contamination, repeated measures are required to optimize the soil reaction, supply with nutrients, and to correct the availability of heavy metals in the soils based on the results of continuous monitoring

  6. Chemical pollution in the Arctic and Sub-Arctic marine ecosystems: an overview of current knowledge

    Energy Technology Data Exchange (ETDEWEB)

    Savinova, T N; Gabrielsen, G W; Falk-Petersen, S

    1995-02-01

    This report is part of a research project in the framework of the Norwegian-Russian Environmental Cooperation, which was initiated in 1991 to elucidate the present status of environmental contaminants in the highly sensitive Arctic aquatic ecosystem, with special focus on sea birds. Although these ecosystems are the least polluted areas in the world, they are contaminated. The main pathways of contamination into Arctic and sub-Arctic marine ecosystems are atmospheric transport, ocean currents and rivers and in some areas, dumping and ship accidents. A literature survey reveals: (1) there is a lack of data from several trophic levels, (2) previous data are difficult to compare with recent data because of increased quality requirement, (3) not much has been done to investigate the effects of contaminants on the cellular level, at individual or population levels. 389 refs., 7 figs., 32 tabs.

  7. "mus co shee": Indigenous Plant Foods and Horticultural Imperialism in the Canadian Sub-Arctic.

    Science.gov (United States)

    Soloway, Beverly

    2015-01-01

    The 17th-century arrival of the Hudson's Bay Company in Rupert's Land disrupted Mushkegowuk (Cree) hunter-gatherer society by replacing the collection of indigenous plant foods with a British planted-food model. Within a hundred years of British contact, new foodways relied upon hunting and gardening, bringing a loss in heritage plant food knowledge. Mushkegowuk living in the sub-arctic today have minimal knowledge of edible indigenous plants. Dependence on limited local gardening or imported grocery store vegetables has affected diet, nutrition, and cultural systems. In addition to exploring plant food gathering and gardening history in the Hudson Bay Lowlands, this paper demonstrates how re-discovering lost foodway knowledge can contribute to the health and well-being of those living in the far north.

  8. Organic iron (III) complexing ligands during an iron enrichment experiment in the western subarctic North Pacific

    Science.gov (United States)

    Kondo, Yoshiko; Takeda, Shigenobu; Nishioka, Jun; Obata, Hajime; Furuya, Ken; Johnson, William Keith; Wong, C. S.

    2008-06-01

    Complexation of iron (III) with natural organic ligands was investigated during a mesoscale iron enrichment experiment in the western subarctic North Pacific (SEEDS II). After the iron infusions, ligand concentrations increased rapidly with subsequent decreases. While the increases of ligands might have been partly influenced by amorphous iron colloids formation (12-29%), most in-situ increases were attributable to the Dilution of the fertilized patch may have contributed to the rapid decreases of the ligands. During the bloom decline, ligand concentration increased again, and the high concentrations persisted for 10 days. The conditional stability constant was not different between inside and outside of the fertilized patch. These results suggest that the chemical speciation of the released iron was strongly affected by formation of the ligands; the production of ligands observed during the bloom decline will strongly impact the iron cycle and bioavailability in the surface water.

  9. Nitrogen fixation, denitrification, and ecosystem nitrogen pools in relation to vegetation development in the Subarctic

    DEFF Research Database (Denmark)

    Sørensen, Pernille Lærkedal; Jonasson, Sven Evert; Michelsen, Anders

    2006-01-01

    Nitrogen (N) fixation, denitrification, and ecosystem pools of nitrogen were measured in three subarctic ecosystem types differing in soil frost-heaving activity and vegetation cover. N2-fixation was measured by the acetylene reduction assay and converted to absolute N ecosystem input by estimates...... of conversion factors between acetylene reduction and 15N incorporation. One aim was to relate nitrogen fluxes and nitrogen pools to the mosaic of ecosystem types of different stability common in areas of soil frost movements. A second aim was to identify abiotic controls on N2-fixation by simultaneous...... measurements of temperature, light, and soil moisture. Nitrogen fixation rate was high with seasonal input estimated at 1.1 g N m2 on frostheaved sorted circles, which was higher than the total plant N content and exceeded estimated annual plant N uptake several-fold but was lower than the microbial N content...

  10. The diversity and abundance of ground herbs in lowland mixed dipterocarp forest and heath forest in Brunei Darussalam

    Directory of Open Access Journals (Sweden)

    Nurul Hazlina Zaini

    2014-12-01

    Full Text Available Herbaceous plants are important components of total plant species richness in tropical forests. Ground herb diversity and abundance were studied in a lowland Mixed Dipterocarp forest (Andulau and a heath forest (Bukit Sawat in Brunei Darussalam, Borneo. At each site, all ground herbs in twenty randomly selected 10 × 10 m subplots within a one hectare permanent plot were censused and identified. The study recorded a total of 20 families and 32 genera of ground herbs, with the family Zingiberaceae as the most abundant at both sites. Thirteen genera were recorded only at Andulau and 7 genera were exclusive to Bukit Sawat, with twelve genera common to both sites. Ground herb species richness appear higher at Andulau than Bukit Sawat (37 vs. 29, but this difference was not statistically significant at the subplot level. However, ground herb abundance and density were significantly higher at Bukit Sawat than Andulau (n =  846 vs. 385; 4230 vs. 1925 individuals ha-1. The more open canopy at Bukit Sawat may provide higher light availability here than at Andulau, which is characterised by a closed canopy. We suggest that light availability is the most important environmental factor influencing ground herb density and abundance at these sites. 

  11. Stem water transport and freeze-thaw xylem embolism in conifers and angiosperms in a Tasmanian treeline heath.

    Science.gov (United States)

    Feild, Taylor S; Brodribb, Tim

    2001-05-01

    The effect of freezing on stem xylem hydraulic conductivity and leaf chlorophyll a fluorescence was measured in 12 tree and shrub species from a treeline heath in Tasmania, Australia. Reduction in stem hydraulic conductivity after a single freeze-thaw cycle was minimal in conifers and the vessel-less angiosperm species Tasmannia lanceolata (Winteraceae), whereas mean loss of conductivity in vessel-forming angiosperms fell in the range 17-83%. A positive linear relationship was observed between percentage loss of hydraulic conductivity by freeze-thaw and the average conduit diameter across all 12 species. This supports the hypothesis that large-diameter vascular conduits have a greater likelihood of freeze-thaw cavitation because larger bubbles are produced, which are more likely to expand under tension. Leaf frost tolerances, as measured by a 50% loss of maximum PSII quantum yield, varied from -6 to -13°C, indicating that these species were more frost-sensitive than plants from northern hemisphere temperate forest and treeline communities. There was no evidence of a relationship between frost tolerance of leaves and the resilience of stem water transport to freezing, suggesting that low temperature survival and the resistance of stem water transport to freezing are independently evolving traits. The results of this study bear on the ecological importance of stem freezing in the southern hemisphere treeline zones.

  12. New species of Drymopsalta Heath Cicadas (Cicadidae: Cicadettinae: Cicadettini) from Queensland and Northern Territory, Australia, with overview of genus.

    Science.gov (United States)

    Ewart, A; Popple, L W

    2013-01-01

    Three new species are described in the genus Drymopsalta Ewart, previously known only from D. crepitum Ewart and D. daemeli Distant. The three new species occur in Southern Queensland and Northern Territory. D. wallumi sp. nov. occurs along coastal S.E. Queensland, whereas D. hobsoni sp. nov. is restricted to the Bringalily State Forest, near Inglewood, southern inland Queensland. D. acrotela sp. nov. is found in the Litchfield National Park and other locations near Jabaluka, Cahills Crossing, E. Alligator River and Nourlangie, all across the northern Northern Territory. D. crepitum occurs on the Cape York Peninsular extending into the southern Gulf, while D. daemeli occurs in two localised regions in central coastal N.S.W. Each of the species inhabits heath vegetation, often spilling-over into adjacent tree foliage. The species of Drymopsalta are small and inconspicuous cicadas (cicadas. Two additional song variants are described, a more unstructured chirping song without intervening single ticks observed in each of the species except D. crepitum, and periodic extended buzzing echemes emitted within the calling songs (excepting the D. wallumi song).

  13. Methanethiol Concentrations and Sea-Air Fluxes in the Subarctic NE Pacific Ocean

    Science.gov (United States)

    Kiene, R. P.; Williams, T. E.; Esson, K.; Tortell, P. D.; Dacey, J. W. H.

    2017-12-01

    Exchange of volatile organic sulfur from the ocean to the atmosphere impacts the global sulfur cycle and the climate system and is thought to occur mainly via the gas dimethylsulfide (DMS). DMS is produced during degradation of the abundant phytoplankton osmolyte dimethylsulfoniopropionate (DMSP) but bacteria can also convert dissolved DMSP into the sulfur gas methanethiol (MeSH). MeSH has been difficult to measure in seawater because of its high chemical and biological reactivity and, thus, information on MeSH concentrations, distribution and sea-air fluxes is limited. We measured MeSH in the northeast subarctic Pacific Ocean in July 2016, along transects with strong phytoplankton abundance gradients. Water samples obtained with Niskin bottles were analyzed for MeSH by purge-and-trap gas chromatography. Depth profiles showed that MeSH concentrations were high near the surface and declined with depth. Surface waters (5 m depth) had an average MeSH concentration of 0.75 nM with concentrations reaching up to 3nM. MeSH concentrations were correlated (r = 0.47) with microbial turnover of dissolved DMSP which ranged up to 236 nM per day. MeSH was also correlated with total DMSP (r = 0.93) and dissolved DMS (r = 0.63), supporting the conclusion that DMSP was a major precursor of MeSH. Surface water MeSH:DMS concentration ratios averaged 0.19 and ranged up to 0.50 indicating that MeSH was a significant fraction of the volatile sulfur pool in surface waters. Sea-air fluxes of MeSH averaged 15% of the combined DMS+MeSH flux, therefore MeSH contributed an important fraction of the sulfur emitted to the atmosphere from the subarctic NE Pacific Ocean.

  14. Intra-basin variability of snowmelt water balance calculations in a subarctic catchment

    Science.gov (United States)

    McCartney, Stephen E.; Carey, Sean K.; Pomeroy, John W.

    2006-03-01

    The intra-basin variability of snowmelt and melt-water runoff hydrology in an 8 km2 subarctic alpine tundra catchment was examined for the 2003 melt period. The catchment, Granger Creek, is within the Wolf Creek Research Basin, Yukon, which is typical of mountain subarctic landscapes in northwestern Canada. The study catchment was segmented into nine internally uniform zones termed hydrological response units (HRUs) based on their similar hydrological, physiographic, vegetation and soil properties. Snow accumulation exhibited significant variability among the HRUs, with greatest snow water equivalent in areas of tall shrub vegetation. Melt began first on southerly exposures and at lower elevations, yet average melt rates for the study period varied little among HRUs with the exception of those with steep aspects. In HRUs with capping organic soils, melt water first infiltrated this surface horizon, satisfying its storage capacity, and then percolated into the frozen mineral substrate. Infiltration and percolation into frozen mineral soils was restricted where melt occurred rapidly and organic soils were thin; in this case, melt-water delivery rates exceeded the frozen mineral soil infiltration rate, resulting in high runoff rates. In contrast, where there were slower melt rates and thick organic soils, infiltration was unlimited and runoff was suppressed. The snow water equivalent had a large impact on runoff volume, as soil storage capacity was quickly surpassed in areas of deep snow, diverting the bulk of melt water laterally to the drainage network. A spatially distributed water balance indicated that the snowmelt freshet was primarily controlled by areas with tall shrub vegetation that accumulate large quantities of snow and by alpine areas with no capping organic soils. The intra-basin water balance variability has important implications for modelling freshet in hydrological models.

  15. Controls and variability of solute and sedimentary fluxes in Arctic and sub-Arctic Environments

    Science.gov (United States)

    Dixon, John

    2015-04-01

    Six major factors consistently emerge as controls on the spatial and temporal variability in sediment and solute fluxes in cold climates. They are climatic, geologic, physiographic or relief, biologic, hydrologic, and regolith factors. The impact of these factors on sediment and solute mass transfer in Arctic and sub-Arctic environments is examined. Comparison of non-glacierized Arctic vs. subarctic drainage basins reveals the effects of these controls. All drainage basins exhibit considerable variability in rates of sediment and solute fluxes. For the non-glacierized drainage basins there is a consistent increase in sediment mass transfer by slope processes and fluvial processes as relief increases. Similarly, a consistent increase in sediment mass transfer by slope and fluvial processes is observed as total precipitation increases. Similar patterns are also observed with respect to solute transport and relief and precipitation. Lithologic factors are most strongly observed in the contrast between volcanic vs. plutonic igneous bedrock substrates. Basins underlain by volcanic rocks display greater mass transfers than those underlain by plutonic rocks. Biologic influences are most strongly expressed by variations in extent of vegetation cover and the degree of human interference, with human impacted basins generating greater fluxes. For glacierized basins the fundamental difference to non-glacierized basins is an overall increase in mean annual mass transfers of sediment and a generally smaller magnitude solute transfer. The principal role of geology is observed with respect to lithology. Catchments underlain by limestone demonstrate substantially greater solute mass transfers than sediment transfer. The influence of relief is seen in the contrast in mass transfers between upland and lowland drainage basins with upland basins generating greater sediment and solute transfers than lowland basins. For glacierized basins the effects of biology and regolith appear to be

  16. Interannual Variability of Carbon Dioxide, Methane and Nitrous Oxide Fluxes in Subarctic European Russian Tundra

    Science.gov (United States)

    Marushchak, M. E.; Voigt, C.; Gil, J.; Lamprecht, R. E.; Trubnikova, T.; Virtanen, T.; Kaverin, D.; Martikainen, P. J.; Biasi, C.

    2017-12-01

    Southern tundra landscapes are particularly vulnerable to climate warming, permafrost thaw and associated landscape rearrangement due to near-zero permafrost temperatures. The large soil C and N stocks of subarctic tundra may create a positive feedback for warming if released to the atmosphere at increased rates. Subarctic tundra in European Russia is a mosaic of land cover types, which all play different roles in the regional greenhouse gas budget. Peat plateaus - massive upheaved permafrost peatlands - are large storehouses of soil carbon and nitrogen, but include also bare peat surfaces that act as hot-spots for both carbon dioxide and nitrous oxide emissions. Tundra wetlands are important for the regional greenhouse gas balance since they show high rates of methane emissions and carbon uptake. The most dominant land-form is upland tundra vegetated by shrubs, lichens and mosses, which displays a close-to-neutral balance with respect to all three greenhouse gases. The study site Seida (67°03'N, 62°56'E), located in the discontinuous permafrost zone of Northeast European Russia, incorporates all these land forms and has been an object for greenhouse gas investigations since 2007. Here, we summarize the growing season fluxes of carbon dioxide, methane and nitrous oxide measured by chamber techniques over the study years. We analyzed the flux time-series together with the local environmental data in order to understand the drivers of interannual variability. Detailed soil profile measurements of greenhouse gas concentrations, soil moisture and temperature provide insights into soil processes underlying the net emissions to the atmosphere. The multiannual time-series allows us to assess the importance of the different greenhouse gases and landforms to the overall climate forcing of the study region.

  17. Microbial control of soil organic matter mineralization responses to labile carbon in subarctic climate change treatments.

    Science.gov (United States)

    Rousk, Kathrin; Michelsen, Anders; Rousk, Johannes

    2016-12-01

    Half the global soil carbon (C) is held in high-latitude systems. Climate change will expose these to warming and a shift towards plant communities with more labile C input. Labile C can also increase the rate of loss of native soil organic matter (SOM); a phenomenon termed 'priming'. We investigated how warming (+1.1 °C over ambient using open top chambers) and litter addition (90 g m -2  yr -1 ) treatments in the subarctic influenced the susceptibility of SOM mineralization to priming, and its microbial underpinnings. Labile C appeared to inhibit the mineralization of C from SOM by up to 60% within hours. In contrast, the mineralization of N from SOM was stimulated by up to 300%. These responses occurred rapidly and were unrelated to microbial successional dynamics, suggesting catabolic responses. Considered separately, the labile C inhibited C mineralization is compatible with previously reported findings termed 'preferential substrate utilization' or 'negative apparent priming', while the stimulated N mineralization responses echo recent reports of 'real priming' of SOM mineralization. However, C and N mineralization responses derived from the same SOM source must be interpreted together: This suggested that the microbial SOM-use decreased in magnitude and shifted to components richer in N. This finding highlights that only considering SOM in terms of C may be simplistic, and will not capture all changes in SOM decomposition. The selective mining for N increased in climate change treatments with higher fungal dominance. In conclusion, labile C appeared to trigger catabolic responses of the resident microbial community that shifted the SOM mining to N-rich components; an effect that increased with higher fungal dominance. Extrapolating from these findings, the predicted shrub expansion in the subarctic could result in an altered microbial use of SOM, selectively mining it for N-rich components, and leading to a reduced total SOM-use. © 2016 John Wiley

  18. Population dynamics and life history strategies of the dominant copepods in a sub-arctic Greenlandic fjord

    DEFF Research Database (Denmark)

    Kjellerup, Sanne; Nielsen, Torkel Gissel

    Investigations of the Arctic and Sub-Arctic pelagic food web have previously focused on the copepod genus Calanus, as they often dominate the mesozooplankton community and serve as a lipid rich food source for higher trophic levels. However, if night samples are considered a different food web...... might emerges with the omnivorous copepod Metridia spp. in a major role. Biology of Metridia is practically unknown but deviates from Calanus e.g. Metridia does not hibernate but stays active yearlong benefiting from being omnivore. In the present study abundance, depth distribution, and egg and pellet...... hibernating Calanus. M. longa might thereby also have a central role in the lipid rich food chain which is a distinct feature for Arctic and Sub-Arctic ecosystems...

  19. Improved resolution of reef-coral endosymbiont (Symbiodinium species diversity, ecology, and evolution through psbA non-coding region genotyping.

    Directory of Open Access Journals (Sweden)

    Todd C LaJeunesse

    Full Text Available Ribosomal DNA sequence data abounds from numerous studies on the dinoflagellate endosymbionts of corals, and yet the multi-copy nature and intragenomic variability of rRNA genes and spacers confound interpretations of symbiont diversity and ecology. Making consistent sense of extensive sequence variation in a meaningful ecological and evolutionary context would benefit from the application of additional genetic markers. Sequences of the non-coding region of the plastid psbA minicircle (psbA(ncr were used to independently examine symbiont genotypic and species diversity found within and between colonies of Hawaiian reef corals in the genus Montipora. A single psbA(ncr haplotype was recovered in most samples through direct sequencing (~80-90% and members of the same internal transcribed spacer region 2 (ITS2 type were phylogenetically differentiated from other ITS2 types by substantial psbA(ncr sequence divergence. The repeated sequencing of bacterially-cloned fragments of psbA(ncr from samples and clonal cultures often recovered a single numerically common haplotype accompanied by rare, highly-similar, sequence variants. When sequence artifacts of cloning and intragenomic variation are factored out, these data indicate that most colonies harbored one dominant Symbiodinium genotype. The cloning and sequencing of ITS2 DNA amplified from these same samples recovered numerically abundant variants (that are diagnostic of distinct Symbiodinium lineages, but also generated a large amount of sequences comprising PCR/cloning artifacts combined with ancestral and/or rare variants that, if incorporated into phylogenetic reconstructions, confound how small sequence differences are interpreted. Finally, psbA(ncr sequence data from a broad sampling of Symbiodinium diversity obtained from various corals throughout the Indo-Pacific were concordant with ITS lineage membership (defined by denaturing gradient gel electrophoresis screening, yet exhibited

  20. Report of the 2004 Workshop on In Situ Iron Enrichment Experiments in the Eastern and Western Subarctic Pacific

    OpenAIRE

    Takeda, Shigenobu; Wong, C.S.

    2006-01-01

    Foreword 1. BACKGROUND AND OBJECTIVES (pdf, 0.1 Mb) 2. 2004 WORKSHOP SUMMARY (pdf, < 0.1 Mb) 2.1. What have we learned from the enrichment experiments? 2.2 What are the outstanding questions? 2.3 Recommendations for SEEDS-II 3. EXTENDED ABSTRACTS OF THE 2004 WORKSHOP 3.1 Synthesis of the Iron Enrichment Experiments: SEEDS and SERIES (pdf, 0.5 Mb) Iron fertilization experiment in the western subarctic Pacific (SEEDS) by At...

  1. Changing times, changing stories: Generational differences in climate change perspectives from four remote indigenous communities in Subarctic Alaska

    Science.gov (United States)

    Herman-Mercer, Nicole M.; Matkin, Elli; Laituri, Melinda J.; Toohey, Ryan C; Massey, Maggie; Elder, Kelly; Schuster, Paul F.; Mutter, Edda A.

    2016-01-01

    Indigenous Arctic and Subarctic communities currently are facing a myriad of social and environmental changes. In response to these changes, studies concerning indigenous knowledge (IK) and climate change vulnerability, resiliency, and adaptation have increased dramatically in recent years. Risks to lives and livelihoods are often the focus of adaptation research; however, the cultural dimensions of climate change are equally important because cultural dimensions inform perceptions of risk. Furthermore, many Arctic and Subarctic IK climate change studies document observations of change and knowledge of the elders and older generations in a community, but few include the perspectives of the younger population. These observations by elders and older generations form a historical baseline record of weather and climate observations in these regions. However, many indigenous Arctic and Subarctic communities are composed of primarily younger residents. We focused on the differences in the cultural dimensions of climate change found between young adults and elders. We outlined the findings from interviews conducted in four indigenous communities in Subarctic Alaska. The findings revealed that (1) intergenerational observations of change were common among interview participants in all four communities, (2) older generations observed more overall change than younger generations interviewed by us, and (3) how change was perceived varied between generations. We defined “observations” as the specific examples of environmental and weather change that were described, whereas “perceptions” referred to the manner in which these observations of change were understood and contextualized by the interview participants. Understanding the differences in generational observations and perceptions of change are key issues in the development of climate change adaptation strategies.

  2. Export production in the subarctic North Pacific over the last 800 kyrs: No evidence for iron fertilization?

    Science.gov (United States)

    Kienast, S.S.; Hendy, I.L.; Crusius, J.; Pedersen, Thomas F.; Calvert, S.E.

    2004-01-01

    The subarctic North Pacific is a high nitrate-low chlorophyll (HNLC) region, where phytoplankton growth rates, especially those of diatoms, are enhanced when micro-nutrient Fe is added. Accordingly, it has been suggested that glacial Fe-laden dust might have increased primary production in this region. This paper reviews published palaeoceanographic records of export production over the last 800 kyrs from the open North Pacific (north of ???35??N). We find different patterns of export production change over time in the various domains of the North Pacific (NW and NE subarctic gyres, the marginal seas and the transition zone). However, there is no compelling evidence for an overall increase in productivity during glacials in the subarctic region, challenging the paradigm that dust-born Fe fertilization of this region has contributed to the glacial draw down of atmospheric CO2. Potential reasons for the lack of increased glacial export production include the possibility that Fe-fertilization rapidly drives the ecosystem towards limitation by another nutrient. This effect would have been exacerbated by an even more stable mixed layer compared to today. ?? The Oceanographic Society of Japan.

  3. Diversity of active aerobic methanotrophs along depth profiles of arctic and subarctic lake water column and sediments

    Science.gov (United States)

    He, Ruo; Wooller, Matthew J.; Pohlman, John W.; Quensen, John; Tiedje, James M.; Leigh, Mary Beth

    2012-01-01

    Methane (CH4) emitted from high-latitude lakes accounts for 2–6% of the global atmospheric CH4 budget. Methanotrophs in lake sediments and water columns mitigate the amount of CH4 that enters the atmosphere, yet their identity and activity in arctic and subarctic lakes are poorly understood. We used stable isotope probing (SIP), quantitative PCR (Q-PCR), pyrosequencing and enrichment cultures to determine the identity and diversity of active aerobic methanotrophs in the water columns and sediments (0–25 cm) from an arctic tundra lake (Lake Qalluuraq) on the north slope of Alaska and a subarctic taiga lake (Lake Killarney) in Alaska's interior. The water column CH4 oxidation potential for these shallow (~2m deep) lakes was greatest in hypoxic bottom water from the subarctic lake. The type II methanotroph, Methylocystis, was prevalent in enrichment cultures of planktonic methanotrophs from the water columns. In the sediments, type I methanotrophs (Methylobacter, Methylosoma and Methylomonas) at the sediment-water interface (0–1 cm) were most active in assimilating CH4, whereas the type I methanotroph Methylobacter and/or type II methanotroph Methylocystis contributed substantially to carbon acquisition in the deeper (15–20 cm) sediments. In addition to methanotrophs, an unexpectedly high abundance of methylotrophs also actively utilized CH4-derived carbon. This study provides new insight into the identity and activity of methanotrophs in the sediments and water from high-latitude lakes.

  4. Characterisation of organic carbon in mire and heath soils at the Elgea-Urkilla Wind Farm, northern Spain

    Directory of Open Access Journals (Sweden)

    Z. Azkorra

    2008-07-01

    Full Text Available This paper describes a detailed comparative study of carbon storage in mire and heath soils within the Elgea-Urkilla Wind Farm (Basque Country, northern Spain. Different methods for estimating organic C stocks in the uppermost 15 cm of the soil profile were evaluated in an attempt to determine whether there was any spatial variability. The dominant vegetation of the study area was acidophilic and Atlantic heathland, with scattered areas of mire vegetation associated with spring lines. Soils were classified as Haplic Leptic Umbrisols (Oxyaquic, Molliglosic. Two sampling plots (900 m2 and 600 m2 were established adjacent to wind turbines. Mire vegetation was present in the larger plot (PLOT-A and absent from the smaller one (PLOT-B. Fourier-transformed infra-red (FTIR spectra indicated no noteworthy structural dissimilarities in the organic matter characteristics of the soils beneath the two types of vegetation. Soil samples were taken every week at systematically chosen points lying on fixed transects. Estimates of organic C stocks based on single sampling dates were 94–141 t C ha-1 for PLOT-A and 70–105 t C ha-1 for PLOT-B, and tended to increase as the weather became drier. When the estimates were derived from samples taken on several dates but from single transects, the range of the estimate for each plot was reduced to 111–116 t ha-1 for PLOT-A and 81–89 t ha-1 for PLOT-B. The results suggest that organic C stocks vary seasonally, and highlight difficulties that may be encountered in attempting to detect long-term changes in C storage.

  5. Association of climatic factors with infectious diseases in the Arctic and subarctic region--a systematic review.

    Science.gov (United States)

    Hedlund, Christina; Blomstedt, Yulia; Schumann, Barbara

    2014-01-01

    The Arctic and subarctic area are likely to be highly affected by climate change, with possible impacts on human health due to effects on food security and infectious diseases. To investigate the evidence for an association between climatic factors and infectious diseases, and to identify the most climate-sensitive diseases and vulnerable populations in the Arctic and subarctic region. A systematic review was conducted. A search was made in PubMed, with the last update in May 2013. Inclusion criteria included human cases of infectious disease as outcome, climate or weather factor as exposure, and Arctic or subarctic areas as study origin. Narrative reviews, case reports, and projection studies were excluded. Abstracts and selected full texts were read and evaluated by two independent readers. A data collection sheet and an adjusted version of the SIGN methodology checklist were used to assess the quality grade of each article. In total, 1953 abstracts were initially found, of which finally 29 articles were included. Almost half of the studies were carried out in Canada (n=14), the rest from Sweden (n=6), Finland (n=4), Norway (n=2), Russia (n=2), and Alaska, US (n=1). Articles were analyzed by disease group: food- and waterborne diseases, vector-borne diseases, airborne viral- and airborne bacterial diseases. Strong evidence was found in our review for an association between climatic factors and food- and waterborne diseases. The scientific evidence for a link between climate and specific vector- and rodent-borne diseases was weak due to that only a few diseases being addressed in more than one publication, although several articles were of very high quality. Air temperature and humidity seem to be important climatic factors to investigate further for viral- and bacterial airborne diseases, but from our results no conclusion about a causal relationship could be drawn. More studies of high quality are needed to investigate the adverse health impacts of weather and

  6. Quantifying dust input to the Subarctic North Pacific - Results from surface sediments and sea water thorium isotope measurements

    Science.gov (United States)

    Winckler, G.; Serno, S.; Hayes, C.; Anderson, R. F.; Gersonde, R.; Haug, G. H.

    2012-12-01

    The Subarctic North Pacific is one of the three primary high-nutrient-low chlorophyll regions of the modern ocean, where the biological pump is relatively inefficient at transferring carbon from the atmosphere to the deep sea. The system is thought to be iron-limited. Aeolian dust is a significant source of iron and other nutrients that are essential for the health of marine ecosystems and potentially a controlling factor of the high-nutrient-low chlorophyll status of the Subarctic North Pacific. However, constraining the size of the dust flux to the surface ocean remains difficult. Here we apply two different approaches, based on surface sediment and water column samples, respectively, obtained during the SO202/INOPEX research cruise to the Subarctic North Pacific in 2009. We map the spatial patterns of Th/U isotopes, helium isotopes and rare earth elements across surface sediments from 37 multi-core core-top sediments across the Subarctic North Pacific. In order to deconvolve the detrital endmembers in regions of the North Pacific affected by volcanic material, IRD and hemipelagic input, we use a combination of trace elements with distinct characteristics in the different endmembers. This approach allows us to calculate the relative aeolian fraction, and in combination with Thorium230-normalized mass flux data, to quantify the dust supply. Secondly, we present an innovative approach to use paired Thorium-232 and Thorium-230 concentrations of upper-ocean seawater at 7 stations along the INOPEX track. Thorium-232 in the upper water column is dominantly derived from dissolution of aeolian dust, whereas Thorium-230 data provide a measure of the thorium removal from the surface waters and, thus, allow us to derive Thorium-232 fluxes. Combined with a mean Thorium-232 concentration in dust and estimate of the thorium solubility, the Thorium-232 flux can be translated in a dust flux to the surface ocean. Dust flux estimates for the Subarctic North Pacific will be

  7. Is the mineralisation response to root exudation controlled by the microbial stoichiometric demand in subarctic soils?

    Science.gov (United States)

    Rousk, Johannes; Hicks, Lettice; Leizeaga, Ainara; Michelsen, Anders; Rousk, Kathrin

    2017-04-01

    Climate change will expose arctic and subarctic systems to warming and a shift towards plant communities with more rhizosphere labile C input. Labile C can also increase the rate of loss of native soil organic matter (SOM); a phenomenon termed 'priming'. We investigated how warming (+1.1˚ C over ambient using open top chambers) and the addition of plant litter (90 g m-2 y-1) or organic nitrogen (N) (fungal fruit bodies; 90 g m-2 y-1) in the Subarctic influenced the susceptibility of SOM mineralisation to priming, and its microbial underpinnings. Root exudation were simulated with the addition of labile organic matter both in the form of only labile C (13C-glucose) or in the form of labile C and N (13C-alanine). We hypothesized that labile C would induce a higher mineralization of N than C sourced from SOM ("N mining"); a response unrelated to microbial growth responses. We also hypothesized that the N mining effect would be more pronounced in climate change simulation treatments of higher C/N (plant litter) than treatments with lower C/N (fungal fruitbodies and warming), with the control treatments intermediate. We also hypothesized that the addition of labile C and N would not result in selective N mining, but instead coupled responses of C and N mineralisation sourced from SOM; a response that would coincide with stimulated microbial growth responses. Labile C appeared to inhibit the mineralisation of C from SOM by up to 60% within hours. In contrast, the mineralisation of N from SOM was stimulated by up to 300%. These responses occurred rapidly and were unrelated to microbial successional dynamics, suggesting catabolic responses. Considered separately, the labile-C inhibited C mineralisation is compatible with previously reported findings termed 'preferential substrate utilisation' or 'negative apparent priming', while the stimulated N mineralisation responses echo recent reports of 'real priming' of SOM mineralisation. However, C and N mineralisation responses

  8. Complex Population Structure of Lyme Borreliosis Group Spirochete Borrelia garinii in Subarctic Eurasia

    Science.gov (United States)

    Comstedt, Pär; Asokliene, Loreta; Eliasson, Ingvar; Olsen, Björn; Wallensten, Anders; Bunikis, Jonas; Bergström, Sven

    2009-01-01

    Borrelia garinii, a causative agent of Lyme borreliosis in Europe and Asia, is naturally maintained in marine and terrestrial enzootic cycles, which primarily involve birds, including seabirds and migratory passerines. These bird groups associate with, correspondingly, Ixodes uriae and Ixodes ricinus ticks, of which the latter species may bite and transmit the infection to humans. Studies of the overlap between these two natural cycles of B. garinii have been limited, in part due to the absence of representative collections of this spirochete's samples, as well as of the lack of reliable measure of the genetic heterogeneity of its strains. As a prerequisite for understanding the epidemiological correlates of the complex maintenance of B. garinii, the present study sought to assess the diversity and phylogenetic relationships of this species' strains from its natural hosts and patients with Lyme borreliosis from subarctic Eurasia. We used sequence typing of the partial rrs-rrl intergenic spacer (IGS) of archived and prospective samples of B. garinii from I. uriae ticks collected predominantly on Commander Islands in North Pacific, as well as on the islands in northern Sweden and arctic Norway. We also typed B. garinii samples from patients with Lyme borreliosis and I. ricinus ticks infesting migratory birds in southern Sweden, or found questing in selected sites on the islands in the Baltic Sea and Lithuania. Fifty-two (68%) of 77 B. garinii samples representing wide geographical range and associated with I. ricinus and infection of humans contributed 12 (60%) of total 20 identified IGS variants. In contrast, the remaining 25 (32%) samples recovered from I. uriae ticks from a few islands accounted for as many as 10 (50%) IGS types, suggesting greater local diversity of B. garinii maintained by seabirds and their ticks. Two IGS variants of the spirochete in common for both tick species were found in I. ricinus larvae from migratory birds, an indication that B

  9. Seasonal and spatial patterns of heterotrophic bacterial production, respiration, and biomass in the subarctic NE Pacific

    Science.gov (United States)

    Sherry, Nelson D.; Boyd, Philip W.; Sugimoto, Kugako; Harrison, Paul J.

    1999-11-01

    Heterotrophic bacterial biomass, production, and respiration rates were measured during winter, spring, and summer in the subarctic NE Pacific from September 1995 to June 1997. Sampling took place on six cruises at five hydrographic stations along the east/west line-P transect from slope waters at P4 (1200 m depth) to the open-ocean waters at Ocean Station Papa (OSP) (4250 m depth). Interannual variability was small relative to seasonal and spatial variability. Biomass, derived from cell counts (assuming 20 fg C cell -1), was ca. 12 μg C l -1 in the winter and increased to 20-35 μg C l -1 in the spring and summer all along line-P. Bacterial production from [ 3H]-thymidine and [ 14C]-leucine incorporation rates was lowest in the winter (ca. 0.5 μg C l -1 d -1) with little spatial variability. Production increased 10-fold in spring at P4 (to ca. 4.5 μg C l -1 d -1). In contrast, only a 2-fold increase in bacterial production was observed over this period at the more oceanic stations. Rates of production in late summer were highest over the annual cycle at all stations ranging from ca. 6 at P4 to ca. 2 μg C l -1 d -1 at OSP. Bacterial (rates increased >10-fold to ca. 100 μg C l -1 d -1 at P4 in the summer, but, interestingly, did not increase from spring to summer at the more oceanic stations. Thus bacterial growth efficiency, defined as production/(production+respiration), decreased in the spring westwards from the slope waters (P4) to the open-ocean (OSP), but increased westwards in the summer. Bacterial production was highly correlated with temperature at OSP ( r2=0.88) and less so at P4 ( r2=0.50). The observed temporal and spatial trends presented in this study suggest that seasonal changes in bacterial biomass were greatly affected by changes in loss processes, that bacterial biomass is regulated by different processes than bacterial production, and that bacterial production alone, without respiration measurements, is not a robust proxy for bacterial

  10. Biogenic emissions of volatile organic compounds from gorse (Ulex europaeus): Diurnal emission fluxes at Kelling Heath, England

    Science.gov (United States)

    Cao, X.-L.; Boissard, C.; Juan, A. J.; Hewitt, C. N.; Gallagher, M.

    1997-08-01

    Volatile organic compound (VOC) emission fluxes from Gorse (Ulex europaeus) were measured during May 30-31, 1995 at Kelling Heath in eastern England by using bag enclosure and gradient methods simultaneously. The enclosure measurements were made from branches at different stages of physiological development (flowering, after flowering, and mixed). Isoprene was found to represent 90% of the total VOC emissions, and its emission rates fluctuated from 6 ng (g dwt)-1 h-1 in the early morning to about 9700 ng(g dwt)-1 h-1 at midday. Averaged emission rates standardized to 20°C were 1625, 2120, and 3700 ng (g dwt)-1 h-1 for the new grown, "mixed," and flowering branch, respectively. Trans-ocimene and α-pinene were the main monoterpenes emitted and represented, on average, 47.6% and 36.9% of the total monoterpenes. Other monoterpenes, camphene, sabinene, β-pinene, myrcene, limonene and γ-terpinene, were positively identified but together represented less than 1.5% of the total VOC emissions from gorse. Maximum isoprene concentrations in air at the site were measured around midday at 2 m (174 parts per trillion by volume, or pptv) and 6 m (149 pptv), and minimum concentrations were measured during the night (8 pptv at both heights). Mean daytime α-pinene air concentrations of 141 and 60 pptv at 2 and 6 m height were determined, but trans-ocimene concentrations were less than the analytical detection limit (4 pptv), suggesting rapid chemical removal of this compound from air. The isoprene fluxes calculated by the micrometeorological gradient method showed a pattern similar to that of those calculated by the enclosure method, with isoprene emission rates maximum at midday (100 μg m-2 h-1) and not detectable during the nighttime. Assessment of the fraction of the site covered by gorse plants enabled an extrapolation of emission fluxes from the enclosure measurements. When averaged over the 2 day experiment, isoprene fluxes of 29.8 and 27.8 μg m-2 h-1 were obtained from

  11. Food web topology and parasites in the pelagic zone of a subarctic lake

    Science.gov (United States)

    Amundsen, Per-Arne; Lafferty, K.D.; Knudsen, R.; Primicerio, R.; Klemetsen, A.; Kuris, A.M.

    2009-01-01

    Parasites permeate trophic webs with their often complex life cycles, but few studies have included parasitism in food web analyses. Here we provide a highly resolved food web from the pelagic zone of a subarctic lake and explore how the incorporation of parasites alters the topology of the web. 2. Parasites used hosts at all trophic levels and increased both food-chain lengths and the total number of trophic levels. Their inclusion in the network analyses more than doubled the number of links and resulted in an increase in important food-web characteristics such as linkage density and connectance. 3. More than half of the parasite taxa were trophically transmitted, exploiting hosts at multiple trophic levels and thus increasing the degree of omnivory in the trophic web. 4. For trophically transmitted parasites, the number of parasite-host links exhibited a positive correlation with the linkage density of the host species, whereas no such relationship was seen for nontrophically transmitted parasites. Our findings suggest that the linkage density of free-living species affects their exposure to trophically transmitted parasites, which may be more likely to adopt highly connected species as hosts during the evolution of complex life cycles. 5. The study supports a prominent role for parasites in ecological networks and demonstrates that their incorporation may substantially alter considerations of food-web structure and functioning. ?? 2009 British Ecological Society.

  12. Seasonal changes in the radiation balance of subarctic forest and tundra

    International Nuclear Information System (INIS)

    Lafleur, P.M.; Renzetti, A.V.; Bello, R.

    1993-01-01

    This paper examines the seasonal behavior of the components of the radiation budget of subarctic tundra and open forest near Churchill, Manitoba. Data were collected between late February and August 1990. The presence of the winter snowpack is the most important factor which affects the difference in radiation balances of tundra and forest. Overall, net radiation was about four to five times larger over the forest when snow covered the ground. Albedo differences were primarily responsible for this difference in net radiation; however, somewhat smaller net longwave losses were experienced at the tundra site. The step decrease in albedo from winter to summer (i.e. snow-covered to snow-free conditions) was significant at both sites. The forest albedo decreased by about three-fold while the tundra experienced a seven-fold decrease. Net radiation at both sites increased in direct response to the albedo change. Transmissivity of the atmosphere near Churchill also appeared to change at about the same time as the loss of the snow cover and may be related to changing air masses which bring about the final snow melt

  13. Rapid responses of permafrost and vegetation to experimentally increased snow cover in sub-arctic Sweden

    International Nuclear Information System (INIS)

    Johansson, Margareta; Bosiö, Julia; Akerman, H Jonas; Jackowicz-Korczynski, Marcin; Christensen, Torben R; Callaghan, Terry V

    2013-01-01

    Increased snow depth already observed, and that predicted for the future are of critical importance to many geophysical and biological processes as well as human activities. The future characteristics of sub-arctic landscapes where permafrost is particularly vulnerable will depend on complex interactions between snow cover, vegetation and permafrost. An experimental manipulation was, therefore, set up on a lowland peat plateau with permafrost, in northernmost Sweden, to simulate projected future increases in winter precipitation and to study their effects on permafrost and vegetation. After seven years of treatment, statistically significant differences between manipulated and control plots were found in mean winter ground temperatures, which were 1.5 ° C higher in manipulated plots. During the winter, a difference in minimum temperatures of up to 9 ° C higher could be found in individual manipulated plots compared with control plots. Active layer thicknesses increased at the manipulated plots by almost 20% compared with the control plots and a mean surface subsidence of 24 cm was recorded in the manipulated plots compared to 5 cm in the control plots. The graminoid Eriophorum vaginatum has expanded in the manipulated plots and the vegetation remained green longer in the season. (letter)

  14. Some factors effecting algal consumption in subarctic Ephemeroptera, Plecoptera, and Simuliidae

    Energy Technology Data Exchange (ETDEWEB)

    Moore, J.W.

    1977-01-01

    Some of the factors influencing algal consumption in the mayflies Leptophlebia nebulosa, Cinygmula tarda, Baetis foemina and B. cf. bicaudatus, the plecopterans Arcynopteryx signata, Nemoura cinctipes and N. oregonensis and in the dipterans Simulium arcticum, S. venustum and S. decorum were investigated between June 1975 and June 1976 in several streams in the Canadian subarctic. Algae represented up to 65% of the gut contents of L. nebulosa but only 0--8% in the other mayflies. They were important in the plecopterans (85--90%) but less so (2--13%) in the simuliids. Most of the interspecies variability in algal consumption could be explained in terms of food availability. This factor was in turn dependent on the density and attachment characteristics of the flora and the strength of their cell wall. Feeding intensity in most species was low between October and April, reaching it peak in July and August. From 51 to 83% of intraspecies feeding variability was due to changing temperature, followed in importance by water velocity in the dipterans and food availability in the mayflies. All species in this latter group ceased feeding in the final instar stages.

  15. Compositional Stability of the Bacterial Community in a Climate-Sensitive Sub-Arctic Peatland.

    Science.gov (United States)

    Weedon, James T; Kowalchuk, George A; Aerts, Rien; Freriks, Stef; Röling, Wilfred F M; van Bodegom, Peter M

    2017-01-01

    The climate sensitivity of microbe-mediated soil processes such as carbon and nitrogen cycling offers an interesting case for evaluating the corresponding sensitivity of microbial community composition to environmental change. Better understanding of the degree of linkage between functional and compositional stability would contribute to ongoing efforts to build mechanistic models aiming at predicting rates of microbe-mediated processes. We used an amplicon sequencing approach to test if previously observed large effects of experimental soil warming on C and N cycle fluxes (50-100% increases) in a sub-arctic Sphagnum peatland were reflected in changes in the composition of the soil bacterial community. We found that treatments that previously induced changes to fluxes did not associate with changes in the phylogenetic composition of the soil bacterial community. For both DNA- and RNA-based analyses, variation in bacterial communities could be explained by the hierarchy: spatial variation (12-15% of variance explained) > temporal variation (7-11%) > climate treatment (4-9%). We conclude that the bacterial community in this environment is stable under changing conditions, despite the previously observed sensitivity of process rates-evidence that microbe-mediated soil processes can alter without concomitant changes in bacterial communities. We propose that progress in linking soil microbial communities to ecosystem processes can be advanced by further investigating the relative importance of community composition effects versus physico-chemical factors in controlling biogeochemical process rates in different contexts.

  16. Increasing frequency of plastic particles ingested by seabirds in the subarctic North Pacific

    Science.gov (United States)

    Robards, Martin D.; Piatt, John F.; Wohl, Kenton D.

    1995-01-01

    We examined gut contents of 1799 seabirds comprising 24 species collected in 1988-1990 to assess the types and quantities of plastic particles ingested by seabirds in the subarctic waters of Alaska. Of the 15 species found to ingest plastic, most were surface-feeders (shearwaters, petrels, gulls) or plankton-feeding divers (auklets, puffins). Of 4417 plastic particles examined, 76% were industrial pellets and 21% were fragments of ‘user’ plastic. Ingestion rates varied geographically, but no trends were evident and rates of plastic ingestion varied far more among species within areas than within species among areas. Comparison with similar data from 1968 seabirds comprising 37 species collected in 1969-1977 revealed that plastic ingestion by seabirds has increased significantly during the 10–15-year interval between studies. This was demonstrated by: (i) an increase in the total number of species ingesting plastic; (ii) an increase in the frequency of occurrence of plastic particles within species that ingested plastic; and, (iii) an increase in the mean number of plastic particles ingested by individuals of those species.

  17. Effects of iron, manganese, copper, and zinc enrichments on productivity and biomass in the subarctic Pacific

    International Nuclear Information System (INIS)

    Coale, K.H.

    1991-01-01

    Natural plankton populations from subarctic Pacific surface waters were incubated in 7-d experiments with added concentrations of Fe, Mn, Cu, and Zn. Small additions of metals were used to simulate natural perturbations in metal concentrations potentially experienced by marine plankton. Trace metal concentrations, phytoplankton productivity, Chl a, and the species composition of phytoplankton and microzooplankton were measured over the course of the experiment. Although the controls indicated little growth, increases in phytoplankton productivity, Chl a, and cell densities were dramatic after the addition of 0.89 nM Fe, indicating that it may limit the rates of algal production in these waters. Similar increases were observed in experiments with 3.9 nM Cu added. The Cu effect is attributed to a decrease in the grazing activities of the microzooplankton and increases in the rates of production. Mn enrichment had its greatest effect on diatom biomass, whereas Zn enrichment had its greatest effect on other autofluorescent organisms. The extent of trace metal adsorption onto carboy walls was also evaluated. These results imply that natural systems may be affected as follows: natural levels of Fe and Cu may influence phytoplankton productivity and trophic structure in open-ocean, high-nutrient, low-biomass systems; rates of net production are not limited by one micronutrient alone

  18. Wintertime pytoplankton bloom in the Subarctic Pacific supportedby continental margin iron

    Energy Technology Data Exchange (ETDEWEB)

    Lam, Phoebe J.; Bishop, James K.B.; Henning, Cara C.; Marcus,Matthew A.; Waychunas, Glenn A.; Fung, Inez

    2004-06-08

    Heightened biological activity was observed in February 1996in the high-nutrient low-chlorophyll (HNLC) subarctic North PacificOcean, a region that is thought to beiron-limited. Here we provideevidence supporting the hypothesis that Ocean Station Papa (OSP) in thesubarctic Pacific received a lateral supply of particulate iron from thecontinental margin off the Aleutian Islands in the winter, coincidentwith the observed biological bloom. Synchrotron X-ray analysis was usedto describe the physical form, chemistry, and depth distributions of ironin size fractionated particulate matter samples. The analysis revealsthat discrete micron-sized iron-rich hotspots are ubiquitous in the upper200m at OSP, more than 900km from the closest coast. The specifics of thechemistry and depth profiles of the Fe hot spots trace them to thecontinental margins. We thus hypothesize that iron hotspots are a markerfor the delivery of iron from the continental margin. We confirm thedelivery of continental margin iron to the open ocean using an oceangeneral circulation model with an iron-like tracer source at thecontinental margin. We suggest that iron from the continental marginstimulated a wintertime phytoplankton bloom, partially relieving the HNLCcondition.

  19. Diverse Mesorhizobium bacteria nodulate native Astragalus and Oxytropis in arctic and subarctic areas in Eurasia.

    Science.gov (United States)

    Ampomah, Osei Yaw; Mousavi, Seyed Abdollah; Lindström, Kristina; Huss-Danell, Kerstin

    2017-01-01

    Rhizobia nodulating native Astragalus and Oxytropis spp. in Northern Europe are not well-studied. In this study, we isolated bacteria from nodules of four Astragalus spp. and two Oxytropis spp. from the arctic and subarctic regions of Sweden and Russia. The phylogenetic analyses were performed by using sequences of three housekeeping genes (16S rRNA, rpoB and recA) and two accessory genes (nodC and nifH). The results of our multilocus sequence analysis (MLSA) of the three housekeeping genes tree showed that all the 13 isolates belonged to the genus Mesorhizobium and were positioned in six clades. Our concatenated housekeeping gene tree also suggested that the isolates nodulating Astragalus inopinatus, Astragalus frigidus, Astragalus alpinus ssp. alpinus and Oxytropis revoluta might be designated as four new Mesorhizobium species. The 13 isolates were grouped in three clades in the nodC and nifH trees. 15 N analysis suggested that the legumes in association with these isolates were actively fixing nitrogen. Copyright © 2016 Elsevier GmbH. All rights reserved.

  20. The Biogeochemical Response to Inter-decadal Atmospheric Forcing Across Watershed Scales in Canada's Subarctic

    Science.gov (United States)

    Spence, C.

    2016-12-01

    Rapid landscape changes in the circumpolar north have been documented, including degradation of permafrost and alteration of vegetation communities. These are widely expected to have profound impacts on the freshwater fluxes of solutes, carbon and nitrogen across the Arctic domain. However, there have been few attempts to document trends across the diversity of landscapes in the circumpolar north, mostly due to a dearth of long term data. Some of the fastest rates of warming over the last thirty years have occurred in Canada's Northwest Territories, so this region should already exhibit changes in aquatic chemistry. Observations of chemical loads in streams draining the ice-poor discontinuous permafrost subarctic Canadian Shield region were analyzed with the goal of determining how basins across scales have responded to changes in atmospheric forcing. Smaller streams, with much closer linkages to terrestrial processes, experienced a synchrony among hydrological and biogeochemical processes that enhanced chemical flux above that in their larger counterparts. This demonstrates that there are differences in resiliency and resistance across scales to climate change. These results highlight the importance of biogeochemical process understanding to properly explain and predict how chemical loading scales from headwaters to river mouths. This is important information if society is to properly adapt policies for effluent discharge, nearshore marine management, among others.

  1. Phytoplankton growth and herbivory in the subarctic Pacific: A chemotaxonomic analysis

    International Nuclear Information System (INIS)

    Welschmeyer, N.; Goericke, R.; Strom, S.; Peterson, W.

    1991-01-01

    Chlorophyll crops in the subarctic Pacific are low and relatively constant throughout the year; however, net growth of phytoplankton occurs when natural water is enclosed in incubation containers and exposed to adequate irradiance. Pigment-based measurements of taxon-specific growth rates and taxon-specific grazing pressure were made in an attempt to understand the dynamic processes leading to the net growth of phytoplankton in bottles. Specific growth rates, determined from 14 C labeling of chromatographically separated pigments showed that fucoxanthin-containing cells (diatoms) were the fastest growing microalgae; a rapid net accumulation of fucoxanthin also occurred. Independent measurements of specific growth rates, determined from chromatographic analysis of microzooplankton dilution experiments, also showed that fucoxanthin-containing cells had the highest specific growth rates. Importantly, microzooplankton grazing rates on fucoxanthin-containing cells were only about half the specific growth rate; hence, the resultant bloom of fucoxanthin. The authors speculate that the lag in chlorophyll growth that has been reported previously is an artifact of subculturing; fast-growing, but dilute, fucoxanthin-containing cells do not become a significant portion of the total chlorophyll signal until late in the experiment. Other diagnostic carotenoids, such as 19'-hexanoyloxyfucoxanthin and 19'-butanoyloxyfucoxanthin, remained nearly constant through long-term incubations. However, they became actively 14 C labeled and showed positive specific rates of growth. Dilution experiments showed that their specific growth rate was compensated by microzooplankton grazing

  2. Modeling a two-layer flow system at the subarctic, subalpine tree line during snowmelt

    Science.gov (United States)

    Leenders, Erica E.; Woo, Ming-Ko

    2002-10-01

    In the subarctic it is common to encounter a two-layer flow system consisting of a porous organic cover overlying frozen or unfrozen mineral soils with much lower hydraulic conductivities. The "simple lumped reservoir parametric," or "semidistributed land-use-based runoff processes" (SLURP), model was adapted to simulate runoff generated by such a flow system from an upland shrub land to an open woodland downslope. A subalpine site in Wolf Creek, Yukon, Canada, was subdivided into two aggregated simulation areas (ASA), each being a unit characterized by a set of parameters. The model computes the vertical water balance and flow generation from several storages, and then routes the water out of the ASA. When applied to the 1999 snowmelt season, the model simulated the very low lateral flow and a large increase in storage in the mineral soil, as was observed in the field. The model was used to assess the sensitivity of the two-layer flow system under a range of temperature, snow cover, and frost conditions. Results show that within the range of possible climatic conditions, the hydrologic system is unlikely to yield significant runoff across the subalpine tree line, but if ground ice is abundant in the soil pores, percolation will be limited and fast flow from the surface layer is enhanced.

  3. UAV Remote Sensing Surveillance of a Mine Tailings Impoundment in Sub-Arctic Conditions

    Directory of Open Access Journals (Sweden)

    Anssi Rauhala

    2017-12-01

    Full Text Available Mining typically involves extensive areas where environmental monitoring is spatially sporadic. New remote sensing techniques and platforms such as Structure from Motion (SfM and unmanned aerial vehicles (UAVs may offer one solution for more comprehensive and spatially continuous measurements. We conducted UAV campaigns in three consecutive summers (2015–2017 at a sub-Arctic mining site where production was temporarily suspended. The aim was to monitor a 0.5 km2 tailings impoundment and measure potential subsidence of tailings. SfM photogrammetry was used to produce yearly topographical models of the tailings surface, which allowed the amount of surface displacement between years to be tracked. Ground checkpoints surveyed in stable areas of the impoundment were utilized in assessing the vertical accuracy of the models. Observed surface displacements were linked to a combination of erosion, tailings settlement, and possible compaction of the peat layer underlying the tailings. The accuracy obtained indicated that UAV-assisted monitoring of tailings impoundments is sufficiently accurate for supporting impoundment management operations and for tracking surface displacements in the decimeter range.

  4. Feasibility analysis of a smart grid photovoltaics system for the subarctic rural region in Alaska

    Science.gov (United States)

    Yao, Lei

    A smart grid photovoltaics system was developed to demonstrate that the system is feasible for a similar off-grid rural community in the subarctic region in Alaska. A system generation algorithm and a system business model were developed to determine feasibility. Based on forecasts by the PV F-Chart software, a 70° tilt angle in winter, and a 34° tilt angle in summer were determined to be the best angles for electrical output. The proposed system's electricity unit cost was calculated at 32.3 cents/kWh that is cheaper than current unsubsidized electricity price (46.8 cents/kWh) in off-grid rural communities. Given 46.8 cents/kWh as the electricity unit price, the system provider can break even when 17.3 percent of the total electrical revenue through power generated by the proposed system is charged. Given these results, the system can be economically feasible during the life-cycle period. With further incentives, the system may have a competitive advantage.

  5. Activity and diversity of methane-oxidizing bacteria along a Norwegian sub-Arctic glacier forefield.

    Science.gov (United States)

    Mateos-Rivera, Alejandro; Øvreås, Lise; Wilson, Bryan; Yde, Jacob C; Finster, Kai W

    2018-05-01

    Methane (CH4) is one of the most abundant greenhouse gases in the atmosphere and identification of its sources and sinks is crucial for the reliability of climate model outputs. Although CH4 production and consumption rates have been reported from a broad spectrum of environments, data obtained from glacier forefields are restricted to a few locations. We report the activities of methanotrophic communities and their diversity along a chronosequence in front of a sub-Arctic glacier using high-throughput sequencing and gas flux measurements. CH4 oxidation rates were measured in the field throughout the growing season during three sampling times at eight different sampling points in combination with laboratory incubation experiments. The overall results showed that the methanotrophic community had similar trends of increased CH4 consumption and increased abundance as a function of soil development and time of year. Sequencing results revealed that the methanotrophic community was dominated by a few OTUs and that a short-term increase in CH4 concentration, as performed in the field measurements, altered slightly the relative abundance of the OTUs.

  6. Habitat quality of a subarctic nursery ground for 0-group plaice ( Pleuronectes platessa L.)

    Science.gov (United States)

    Freitas, Vânia; Campos, Joana; Skreslet, Stig; van der Veer, Henk W.

    2010-07-01

    Habitat quality of a subarctic nursery ground in northern Norway for 0-group plaice Pleuronectes platessa was investigated by following settlement, mortality and growth during 2005 and 2006. Newly settled individuals were first observed in the end of May to early June and settlement lasted until mid-July. Densities peaked in early July and were comparable to those reported in temperate nursery grounds. Mortality estimates after settlement differed between 0.062 d -1 in 2005 and 0.025 d -1 in 2006. Potential predators appeared to be rather similar as those reported in other areas: the brown shrimp Crangoncrangon, the shore crab Carcinus maenas and demersal fish species (gadoids). Population mean growth indicated linear growth until August leveling-off afterwards. 0-group plaice reached a lower mean size (5-6 cm) at the end of the growing season than in temperate areas probably due to later settlement timing in combination with lower summer-autumn water temperatures. The comparison of observed growth rates with predictions of maximum growth models indicated a similar pattern as observed in temperate nursery grounds: Growth appeared to be maximal except for the period after summer. Whether or not this was related to changes in food quality throughout the season, to interspecies competition or to emigration remains to be elucidated.

  7. The relative contributions of biological and abiotic processes to carbon dynamics in subarctic sea ice

    DEFF Research Database (Denmark)

    Søgaard, Dorte Haubjerg; Thomas, David; Rysgaard, Søren

    2013-01-01

    Knowledge on the relative effects of biological activity and precipitation/dissolution of calcium carbonate (CaCO3) in influencing the air-ice CO2 exchange in sea-ice-covered season is currently lacking. Furthermore, the spatial and temporal occurrence of CaCO3 and other biogeochemical parameters...... in sea ice are still not well described. Here we investigated autotrophic and heterotrophic activity as well as the precipitation/dissolution of CaCO3 in subarctic sea ice in South West Greenland. Integrated over the entire ice season (71 days), the sea ice was net autotrophic with a net carbon fixation...... and CaCO3 precipitation. The net biological production could only explain 4 % of this sea-ice-driven CO2 uptake. Abiotic processes contributed to an air-sea CO2 uptake of 1.5 mmol m(-2) sea ice day(-1), and dissolution of CaCO3 increased the air-sea CO2 uptake by 36 % compared to a theoretical estimate...

  8. The Heath Occupational Model.

    Science.gov (United States)

    Heath, William E.

    1990-01-01

    Career development programs must identify occupational needs of adults. A model based on Maslow's hierarchy develops occupational questions related to individual motivations (physiology, safety, love, esteem, and self-actualization). Individual needs are then compared with characteristics and benefits of proposed jobs, companies, or careers. (SK)

  9. Tree species diversity in a seasonally-dry forest: the case of the Pinkaití site, in the Kayapó Indigenous Area, Southeastern limits of the Amazon

    OpenAIRE

    Salm,Rodolfo

    2004-01-01

    This study investigates patterns of forest structure and tree species diversity in an anthropogenic palm grove and undisturbed areas at the seasonally-dry Pinkaití research station, in the Kayapó Indigenous Area. This site, managed by the Conservation International do Brasil, is the most southeastern site floristically surveyed in the Amazon until now. The secondary and a nearby undisturbed forest were sampled in a group of 52 floristic plots of 0.0625-ha (25x25-m) where all trees with DBH > ...

  10. Nitrogen deposition drives loss of moss cover in alpine moss-sedge heath via lowered C : N ratio and accelerated decomposition.

    Science.gov (United States)

    Britton, Andrea J; Mitchell, Ruth J; Fisher, Julia M; Riach, David J; Taylor, Andy F S

    2018-04-01

    In alpine ecosystems, nitrogen (N) deposition has been linked to plant community composition change, including loss of bryophytes and increase of graminoids. Since bryophyte growth is stimulated by increased N availability, it has been hypothesized that loss of bryophyte cover is driven by enhanced decomposition. As bryophyte mats are a significant carbon (C) store, their loss may impact C storage in these ecosystems. We used an N deposition gradient across 15 sites in the UK to examine effects of N deposition on bryophyte litter quality, decomposition and C and N stocks in Racomitrium moss-sedge heath. Increasing N deposition reduced C : N in bryophyte litter, which in turn enhanced decomposition. Soil N stocks increased significantly in response to increased N deposition, and soil C : N declined. However, depletion of the bryophyte mat and its replacement by graminoids under high N deposition was not associated with a change in total ecosystem C stocks. We conclude that decomposition processes in Racomitrium heath are very sensitive to N deposition and provide a mechanism by which N deposition drives depletion of the bryophyte mat. Nitrogen deposition did not measurably alter C stocks, but changes in soil N stocks and C : N suggest the ecosystem is becoming N saturated. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

  11. Development and application of sedimentary pigments for assessing effects of climatic and environmental changes on subarctic lakes in northern Sweden

    DEFF Research Database (Denmark)

    Reuss, Nina Steenberg; Leavitt, Peter R.; Hall, Roland I.

    2010-01-01

    to the modern tree line. The spatial survey of sedimentary pigments was analyzed using principle components analysis (PCA) and redundancy analysis (RDA). PCA explained 73-83% of variance in pigment abundance and composition, whereas RDA explained 22-32% of variation in fossil assemblages. Dissolved organic...... transitions in the phototrophic community during the late Holocene were less easily interpreted. Terrestrial vegetation development thus appears to be of utmost importance for the regulation of primary production in oligotrophic alpine and subarctic lakes and climate impacts on lakes, whereas other basin...

  12. Impacts of twenty years of experimental warming on soil carbon, nitrogen, moisture and soil across alpine/subarctic tundra communities

    DEFF Research Database (Denmark)

    M. Alatalo, Juha; K. Jägerbrand, Annika; Juhanson, Jaanis

    2017-01-01

    High-altitude and alpine areas are predicted to experience rapid and substantial increases in future temperature, which may have serious impacts on soil carbon, nutrient and soil fauna. Here we report the impact of 20 years of experimental warming on soil properties and soil mites in three...... contrasting plant communities in alpine/subarctic Sweden. Long-term warming decreased juvenile oribatid mite density, but had no effect on adult oribatids density, total mite density, any major mite group or the most common species. Long-term warming also caused loss of nitrogen, carbon and moisture from...

  13. Wetland development, permafrost history and nutrient cycling inferred from late Holocene peat and lake sediment records in subarctic Sweden

    DEFF Research Database (Denmark)

    Kokfelt, U.; Reuss, N.; Struyf, E.

    2010-01-01

    to re-deposition of peat into one of the lakes after ca. 2,100 cal BP, and stimulated primary productivity in the other lake at ca. 1,900-1,800 cal BP. Carbonate precipitation appears to have been suppressed when acidic poor fen and bog (palsa) communities dominated the catchment mire, and permafrost...... insight into nutrient and permafrost dynamics in a subarctic wetland and imply that continued permafrost decay and related vegetation changes towards minerotrophy may increase carbon and nutrient storage of mire deposits and reduce nutrient fluxes in runoff. Rapid permafrost degradation may on the other...

  14. Distributions and seasonal abundances of krill eggs and larvae in the sub-Arctic Godthåbsfjord, SW Greenland

    DEFF Research Database (Denmark)

    Teglhus, Frederik Wolff; Agersted, Mette Dalgaard; Akther, Hasna

    2015-01-01

    The larval krill community (Thysanoessa spp.) was investigated along the sub-Arctic Godthåbsfjord, SW Greenland, in June 2010. In addition, the progress of krill development from egg to furcilia was studied from March to August 2010 in a fjord branching off the Godthåbsfjord. Krill spawned from...... and furcilia stages lasted 22 and 63 d, respectively. The growth rate from metanauplius to calyptopis was 0.12 d−1, while the growth rate across all developmental stages was 0.05 d−1. Mortality rates were calculated as 25% from eggs to nauplii, 48% from eggs to calyptopes and 83% from eggs to furcilia. During...

  15. Macrozoobenthos in the subarctic river Tenojoki as an environmental indicator. Tenojoen pohjaelaeimistoe ympaeristoen laadun kuvaajana

    Energy Technology Data Exchange (ETDEWEB)

    Lax, H.G.; Koskenniemi, E.; Sevola, P.; Bagge, P.

    1993-01-01

    The macrozoobenthos of the subarctic river Tenojoki and some of its tributaries was studied in June and September 1989 as a part of the environmental monitoring programme. The river (F = 16 386 km[sup 2], length 300 km, L = 2.4 %, Q varies between 30-400 m[sup 3]/s) is situated on the Finnish-Norwegian border and is characterized by sand bottoms interrupted by shorter reaches of gravel and stone bottoms. The water is usually clear (colour < 40 mg Pt/l) and oligotrophic (tot-P < 10 [mu]g/l). The bottom fauna was sampled from 9 stations in the main river and from one station in each of the 5 major tributaries. The sampling methods used were: kick-sampling and imago hand netting from all stations, colonization substrates (stone baskets and bricks) at 9 stations in the main river. The tax a number of the kick-samples varied from 10-15/station in spring (totally 51 taxa) and from 15-25/station in autumn (totally 69 taxa). In spring the river margin (depth 0-25 cm) seemed to be an important habitat for many species especially in the upper parts of the river. In autumn most of the species occurred on deeper bottoms (depth 50-100 cm). The most common feeding types in spring were the collectors (Amaletus inopinatus, Chironomidae) and in autumn the scrapers (Elmidae, Baetidae, Hydroptllidae) and collectors (Chironomidae). The pollution index (LongScoreSystem) indicated that the conditions in the lower part of the main river was more stressing for the bottom fauna than in the upper part. But up to now it seems as if the organic pollution from settlements have had only positive effects on the benthic community

  16. pH gradients in the diffusive boundary layer of subarctic macrophytes

    KAUST Repository

    Hendriks, Iris E.; Duarte, Carlos M.; Marbà , Nú ria; Krause-Jensen, Dorte

    2017-01-01

    Highly productive macrophytes produce diurnal and seasonal cycles in CO concentrations modulated by metabolic activity, which cause discrepancies between pH in the bulk water and near seaweed blades, especially when entering the diffusion boundary layer (DBL). Calcifying epiphytic organisms living in this environment are therefore exposed to a different pH environment than that of the water column. To evaluate the actual pH environment on blade surfaces, we measured the thickness of the DBL and pH gradients within it for six subarctic macrophytes: Fucus vesiculosus, Ascophyllum nodosum, Ulva lactuca, Zostera marina, Saccharina longicruris, and Agarum clathratum. We measured pH under laboratory conditions at ambient temperatures (2–3 °C) and slow, stable flow over the blade surface at five light intensities (dark, 30, 50, 100 and 200 µmol photons m s). Boundary layer thickness ranged between 511 and 1632 µm, while the maximum difference in pH (∆pH) between the blade surface and the water column ranged between 0.4 ± 0.14 (average ± SE; Zostera) and 1.2 ± 0.13 (average ± SE; Ulva) pH units. These differences in pH are larger than predictions for pH changes in the bulk water by the end of the century. A simple quadratic model best described the relationship between light intensity and maximum ∆pH, pointing at relatively low optimum PAR of between 28 and 139 µmol photons m s to reach maximum ∆pH. Elevated pH at the blade surface may provide chemical “refugia” for calcifying epiphytic organisms, especially during summer at higher latitudes where photoperiods are long.

  17. Metagenomic Insights Into the Microbial Community and Nutrient Cycling in the Western Subarctic Pacific Ocean

    Directory of Open Access Journals (Sweden)

    Yingdong Li

    2018-04-01

    Full Text Available The composition and metabolic functions of prokaryotic communities in the western subarctic Pacific (WSP, where strong mixing of waters from the Sea of Okhotsk and the East Kamchatka Current result in transfer to the Oyashio Current, were investigated using a shotgun metagenome sequencing approach. Functional metabolic genes related to nutrient cycling of nitrogen, sulfur, carbohydrates, iron and amino acids were differently distributed between the surface and deep waters of the WSP. Genes related to nitrogen metabolism were mainly found in deep waters, where Thaumarchaeaota, Sphingomonadales, and Pseudomonadales were closely associated and performing important roles in ammonia oxidation, assimilatory nitrate reduction, and dissimilatory nitrate reduction processes, respectively. In addition, orders affiliated to Spingobacteria and Alphaproteobacteria were crucial for sulfate reduction and abundant at 3000 m, whereas orders affiliated to Gammaproteobacteria, which harbored the most sulfate reduction genes, were abundant at 1000 m. Additionally, when compared with the East Kamchatka Current, the prokaryotes in the Oyashio Current were likely to consume more energy for synthesizing cellular components. Also, genes encoding iron transport and siderophore biosynthesis proteins were in low abundance, indicating that the iron was not a limiting factor in the Oyashio current. In contrast, in the East Kamchatka Current, prokaryotes were more likely to directly utilize the amino acids and absorb iron from the environment. Overall, our data indicated that the transformation from the East Kamchatka Current to the Oyashio Current reshapes not only the composition of microbial community, but also the function of the metabolic processes. These results extended our knowledge of the microbial composition and potential metabolism in the WSP.

  18. Metagenomic Insights Into the Microbial Community and Nutrient Cycling in the Western Subarctic Pacific Ocean.

    Science.gov (United States)

    Li, Yingdong; Jing, Hongmei; Xia, Xiaomin; Cheung, Shunyan; Suzuki, Koji; Liu, Hongbin

    2018-01-01

    The composition and metabolic functions of prokaryotic communities in the western subarctic Pacific (WSP), where strong mixing of waters from the Sea of Okhotsk and the East Kamchatka Current result in transfer to the Oyashio Current, were investigated using a shotgun metagenome sequencing approach. Functional metabolic genes related to nutrient cycling of nitrogen, sulfur, carbohydrates, iron and amino acids were differently distributed between the surface and deep waters of the WSP. Genes related to nitrogen metabolism were mainly found in deep waters, where Thaumarchaeaota, Sphingomonadales , and Pseudomonadales were closely associated and performing important roles in ammonia oxidation, assimilatory nitrate reduction, and dissimilatory nitrate reduction processes, respectively. In addition, orders affiliated to Spingobacteria and Alphaproteobacteria were crucial for sulfate reduction and abundant at 3000 m, whereas orders affiliated to Gammaproteobacteria , which harbored the most sulfate reduction genes, were abundant at 1000 m. Additionally, when compared with the East Kamchatka Current, the prokaryotes in the Oyashio Current were likely to consume more energy for synthesizing cellular components. Also, genes encoding iron transport and siderophore biosynthesis proteins were in low abundance, indicating that the iron was not a limiting factor in the Oyashio current. In contrast, in the East Kamchatka Current, prokaryotes were more likely to directly utilize the amino acids and absorb iron from the environment. Overall, our data indicated that the transformation from the East Kamchatka Current to the Oyashio Current reshapes not only the composition of microbial community, but also the function of the metabolic processes. These results extended our knowledge of the microbial composition and potential metabolism in the WSP.

  19. Observing Trace Gases Of The Arctic And Subarctic Stratosphere By TELIS

    Science.gov (United States)

    Xu, Jian; Schreier, Franz; Doicu, Adrian; Vogt, Peter; Birk, Manfred; Wagner, Georg; Trautmann, Thomas

    2013-12-01

    The Terahertz and submillimeter Limb Sounder (TELIS) is a balloon-borne cryogenic heterodyne spectrometer developed by a consortium of European institutes, which was mounted together with the Michelson Interferometer for Passive Atmospheric Sounding - Balloon (MIPAS- B) and the mini- Differential Optical Absorption Spectroscopy (mini-DOAS) instruments on a stratospheric gondola. The TELIS instrument is designed to monitor the vertical distribution of stratospheric state parameters associated with ozone destruction and climate change in Arctic and subarctic areas. The broad spectral coverage of TELIS is achieved by utilizing three frequency channels: a tunable 1.8THz channel based on a solid state local oscillator and a hot electron bolometer as mixer, a 480-650GHz channel with the Superconducting Integrated Receiver (SIR) technology, and a highly compact 500 GHz channel developed by the German Aerospace Center (DLR), the Netherlands Institute for Space Research (SRON), and the Rutherford Apple- ton Laboratory (RAL), respectively. Furthermore, an ex- tended spectral range is observed by the combination of TELIS and MIPAS-B, which can be employed for cross validation of several gas concentrations. Between 2009 and 2011 three successful scientific flights have been launched in Kiruna, Sweden and all relevant atmospheric gas species were seen by TELIS over an altitude range of 10-32.5 km. For estimation of concentration profiles from TELIS measurements, a constrained nonlinear least squares fitting framework along with var- ious Tikhonov-type regularization methods has been developed. In this work we present recent retrieval results from latest calibrated spectra during the 2010 flight. Emphasis is placed on ozone (O3) and hydrogen chloride (HCl), and error issues pertaining to the main instrumental uncertainty terms including nonlinearity in the calibration procedure, sideband ratio and pointing offset are investigated. The retrieved profiles are validated against

  20. Reconciling biodiversity conservation and agricultural expansion in the subarctic environment of Iceland

    Directory of Open Access Journals (Sweden)

    Lilja Jóhannesdóttir

    2017-03-01

    before further substantial changes in the extent of agriculture take place in this subarctic landscape.

  1. Diversity and population structure of Marine Group A bacteria in the Northeast subarctic Pacific Ocean.

    Science.gov (United States)

    Allers, Elke; Wright, Jody J; Konwar, Kishori M; Howes, Charles G; Beneze, Erica; Hallam, Steven J; Sullivan, Matthew B

    2013-02-01

    Marine Group A (MGA) is a candidate phylum of Bacteria that is ubiquitous and abundant in the ocean. Despite being prevalent, the structural and functional properties of MGA populations remain poorly constrained. Here, we quantified MGA diversity and population structure in relation to nutrients and O(2) concentrations in the oxygen minimum zone (OMZ) of the Northeast subarctic Pacific Ocean using a combination of catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) and 16S small subunit ribosomal RNA (16S rRNA) gene sequencing (clone libraries and 454-pyrotags). Estimates of MGA abundance as a proportion of total bacteria were similar across all three methods although estimates based on CARD-FISH were consistently lower in the OMZ (5.6%±1.9%) than estimates based on 16S rRNA gene clone libraries (11.0%±3.9%) or pyrotags (9.9%±1.8%). Five previously defined MGA subgroups were recovered in 16S rRNA gene clone libraries and five novel subgroups were defined (HF770D10, P262000D03, P41300E03, P262000N21 and A714018). Rarefaction analysis of pyrotag data indicated that the ultimate richness of MGA was very nearly sampled. Spearman's rank analysis of MGA abundances by CARD-FISH and O(2) concentrations resulted in significant correlation. Analyzed in more detail by 16S rRNA pyrotag sequencing, MGA operational taxonomic units affiliated with subgroups Arctic95A-2 and A714018 comprised 0.3-2.4% of total bacterial sequences and displayed strong correlations with decreasing O(2) concentration. This study is the first comprehensive description of MGA diversity using complementary techniques. These results provide a phylogenetic framework for interpreting future studies on ecotype selection among MGA subgroups, and suggest a potentially important role for MGA in the ecology and biogeochemistry of OMZs.

  2. Growth, development, and nutritional physiology of grasshoppers from subarctic and temperate regions.

    Science.gov (United States)

    Fielding, Dennis J; Defoliart, Linda S

    2007-01-01

    Despite the importance of developmental rate, growth rate, and size at maturity in the life history of poikliotherms, the trade-offs among these traits and selection pressures involved in the evolution of these traits are not well understood. This study compared these traits in a grasshopper, Melanoplus sanguinipes F. (Orthoptera: Acrididae), from two contrasting geographical regions, subarctic Alaska and temperate Idaho. The growing season in the interior of Alaska is about 80 d shorter than at low-elevation sites in Idaho. We hypothesized that the Alaskan grasshoppers would show more rapid growth and development than grasshoppers from Idaho, at the cost of greater sensitivity to food quality. On a diet of lettuce and wheat bran, grasshoppers from Alaska developed from egg hatch to adult more rapidly than those from Idaho at each of three different temperature regimes. Averaged over all temperature treatments, the weight of the Alaskan grasshoppers was about 5% less than that of the Idaho grasshoppers at the adult molt. Feeding and digestive efficiencies were determined for the final two instars using two meridic diets: one with a high concentration of nutrients and the other with the same formulation but diluted with cellulose. Alaskan grasshoppers again developed more rapidly, weighed less, and had faster growth rates than those from Idaho. Alaskan grasshoppers supported their more rapid growth by increasing postingestive efficiencies; that is, they had higher conversion rates of digested matter to biomass on the high-quality diet, greater assimilation of food on the low-quality diet, and greater efficiency of nitrogen assimilation or retention on both diets. There was no evidence that performance of Alaskan grasshoppers suffered any more than that of the Idaho grasshoppers on the low-quality diet.

  3. Ozone variability and halogen oxidation within the Arctic and sub-Arctic springtime boundary layer

    Directory of Open Access Journals (Sweden)

    J. B. Gilman

    2010-11-01

    Full Text Available The influence of halogen oxidation on the variabilities of ozone (O3 and volatile organic compounds (VOCs within the Arctic and sub-Arctic atmospheric boundary layer was investigated using field measurements from multiple campaigns conducted in March and April 2008 as part of the POLARCAT project. For the ship-based measurements, a high degree of correlation (r = 0.98 for 544 data points collected north of 68° N was observed between the acetylene to benzene ratio, used as a marker for chlorine and bromine oxidation, and O3 signifying the vast influence of halogen oxidation throughout the ice-free regions of the North Atlantic. Concurrent airborne and ground-based measurements in the Alaskan Arctic substantiated this correlation and were used to demonstrate that halogen oxidation influenced O3 variability throughout the Arctic boundary layer during these springtime studies. Measurements aboard the R/V Knorr in the North Atlantic and Arctic Oceans provided a unique view of the transport of O3-poor air masses from the Arctic Basin to latitudes as far south as 52° N. FLEXPART, a Lagrangian transport model, was used to quantitatively determine the exposure of air masses encountered by the ship to first-year ice (FYI, multi-year ice (MYI, and total ICE (FYI+MYI. O3 anti-correlated with the modeled total ICE tracer (r = −0.86 indicating that up to 73% of the O3 variability measured in the Arctic marine boundary layer could be related to sea ice exposure.

  4. Metagenomic Insights Into the Microbial Community and Nutrient Cycling in the Western Subarctic Pacific Ocean

    Science.gov (United States)

    Li, Yingdong; Jing, Hongmei; Xia, Xiaomin; Cheung, Shunyan; Suzuki, Koji; Liu, Hongbin

    2018-01-01

    The composition and metabolic functions of prokaryotic communities in the western subarctic Pacific (WSP), where strong mixing of waters from the Sea of Okhotsk and the East Kamchatka Current result in transfer to the Oyashio Current, were investigated using a shotgun metagenome sequencing approach. Functional metabolic genes related to nutrient cycling of nitrogen, sulfur, carbohydrates, iron and amino acids were differently distributed between the surface and deep waters of the WSP. Genes related to nitrogen metabolism were mainly found in deep waters, where Thaumarchaeaota, Sphingomonadales, and Pseudomonadales were closely associated and performing important roles in ammonia oxidation, assimilatory nitrate reduction, and dissimilatory nitrate reduction processes, respectively. In addition, orders affiliated to Spingobacteria and Alphaproteobacteria were crucial for sulfate reduction and abundant at 3000 m, whereas orders affiliated to Gammaproteobacteria, which harbored the most sulfate reduction genes, were abundant at 1000 m. Additionally, when compared with the East Kamchatka Current, the prokaryotes in the Oyashio Current were likely to consume more energy for synthesizing cellular components. Also, genes encoding iron transport and siderophore biosynthesis proteins were in low abundance, indicating that the iron was not a limiting factor in the Oyashio current. In contrast, in the East Kamchatka Current, prokaryotes were more likely to directly utilize the amino acids and absorb iron from the environment. Overall, our data indicated that the transformation from the East Kamchatka Current to the Oyashio Current reshapes not only the composition of microbial community, but also the function of the metabolic processes. These results extended our knowledge of the microbial composition and potential metabolism in the WSP. PMID:29670596

  5. pH gradients in the diffusive boundary layer of subarctic macrophytes

    KAUST Repository

    Hendriks, Iris E.

    2017-06-20

    Highly productive macrophytes produce diurnal and seasonal cycles in CO concentrations modulated by metabolic activity, which cause discrepancies between pH in the bulk water and near seaweed blades, especially when entering the diffusion boundary layer (DBL). Calcifying epiphytic organisms living in this environment are therefore exposed to a different pH environment than that of the water column. To evaluate the actual pH environment on blade surfaces, we measured the thickness of the DBL and pH gradients within it for six subarctic macrophytes: Fucus vesiculosus, Ascophyllum nodosum, Ulva lactuca, Zostera marina, Saccharina longicruris, and Agarum clathratum. We measured pH under laboratory conditions at ambient temperatures (2–3 °C) and slow, stable flow over the blade surface at five light intensities (dark, 30, 50, 100 and 200 µmol photons m s). Boundary layer thickness ranged between 511 and 1632 µm, while the maximum difference in pH (∆pH) between the blade surface and the water column ranged between 0.4 ± 0.14 (average ± SE; Zostera) and 1.2 ± 0.13 (average ± SE; Ulva) pH units. These differences in pH are larger than predictions for pH changes in the bulk water by the end of the century. A simple quadratic model best described the relationship between light intensity and maximum ∆pH, pointing at relatively low optimum PAR of between 28 and 139 µmol photons m s to reach maximum ∆pH. Elevated pH at the blade surface may provide chemical “refugia” for calcifying epiphytic organisms, especially during summer at higher latitudes where photoperiods are long.

  6. Polychlorinated naphthalenes (PCNs) in sub-Arctic and Arctic marine mammals, 1986–2009

    International Nuclear Information System (INIS)

    Rotander, Anna; Bavel, Bert van; Rigét, Frank; Auðunsson, Guðjón Atli; Polder, Anuschka; Gabrielsen, Geir Wing; Víkingsson, Gísli; Mikkelsen, Bjarni; Dam, Maria

    2012-01-01

    A selection of PCN congeners was analyzed in pooled blubber samples of pilot whale (Globicephala melas), ringed seal (Phoca hispida), minke whale (Balaenoptera acutorostrata), fin whale (Balaenoptera physalus), harbour porpoise (Phocoena phocoena), hooded seal (Cystophora cristata) and Atlantic white-sided dolphin (Lagenorhynchus acutus), covering a time period of more than 20 years (1986–2009). A large geographical area of the North Atlantic and Arctic areas was covered. PCN congeners 48, 52, 53, 66 and 69 were found in the blubber samples between 0.03 and 5.9 ng/g lw. Also PCBs were analyzed in minke whales and fin whales from Iceland and the total PCN content accounted for 0.2% or less of the total non-planar PCB content. No statistically significant trend in contaminant levels could be established for the studied areas. However, in all species except minke whales caught off Norway the lowest ∑PCN concentrations were found in samples from the latest sampling period. - Highlights: ► PCN concentrations are described in a wide variety of marine mammal species. ► A large geographical area of the North Atlantic and Arctic areas is covered. ► Pooled blubber samples covering a time period of 23 years are evaluated. ► Species- and geographic-dependent PCN congener distribution is seen. ► A decrease in the PCN load is indicated in the studied areas in recent years. - Analysis of PCNs in seven marine mammal species sampled over a 23 year period indicates a decline in the PCN load in sub-Arctic and Arctic areas in recent years.

  7. Microbial biomass dynamics dominate N cycle responses to warming in a sub-arctic peatland

    Science.gov (United States)

    Weedon, J. T.; Aerts, R.; Kowalchuk, G. K.; van Bodegom, P. M.

    2012-04-01

    The balance of primary production and decomposition in sub-arctic peatlands may shift with climate change. Nitrogen availability will modulate this shift, but little is known about the drivers of soil nitrogen dynamics in these environments, and how they are influenced by rising soil temperatures. We used a long-term open top chamber warming experiment in Abisko, Sweden, to test for the interactive effects of spring warming, summer warming and winter snow addition on soil organic and inorganic nitrogen fluxes, potential activities of carbon and nitrogen cycle enzymes, and the structure of the soil-borne microbial communities. Summer warming increased the flux of soil organic nitrogen over the growing season, while simultaneously causing a seasonal decrease in microbial biomass, suggesting that N flux is driven by large late-season dieback of microbes. This change in N cycle dynamics was not reflected in any of the measured potential enzyme activities. Moreover, the soil microbial community structure was stable across treatments, suggesting non-specific microbial dieback. To further test whether the observed patterns were driven by direct temperature effects or indirect effects (via microbial biomass dynamics), we conducted follow-up controlled experiments in soil mesocosms. Experimental additions of dead microbial cells had stronger effects on N pool sizes and enzyme activities than either plant litter addition or a 5 °C alteration in incubation temperatures. Peat respiration was positively affected by both substrate addition and higher incubation temperatures, but the temperature-only effect was not sufficient to account for the increases in respiration observed in previous field experiments. We conclude that warming effects on peatland N cycling (and to some extent C cycling) are dominated by indirect effects, acting through alterations to the seasonal flux of microbe-derived organic matter. We propose that climate change models of soil carbon and nitrogen

  8. The Arctic-Subarctic Sea Ice System is Entering a Seasonal Regime: Implications for Future Arctic Amplication

    Science.gov (United States)

    Haine, T. W. N.; Martin, T.

    2017-12-01

    The loss of Arctic sea ice is a conspicuous example of climate change. Climate models project ice-free conditions during summer this century under realistic emission scenarios, reflecting the increase in seasonality in ice cover. To quantify the increased seasonality in the Arctic-Subarctic sea ice system, we define a non-dimensional seasonality number for sea ice extent, area, and volume from satellite data and realistic coupled climate models. We show that the Arctic-Subarctic, i.e. the northern hemisphere, sea ice now exhibits similar levels of seasonality to the Antarctic, which is in a seasonal regime without significant change since satellite observations began in 1979. Realistic climate models suggest that this transition to the seasonal regime is being accompanied by a maximum in Arctic amplification, which is the faster warming of Arctic latitudes compared to the global mean, in the 2010s. The strong link points to a peak in sea-ice-related feedbacks that occurs long before the Arctic becomes ice-free in summer.

  9. Effects of a controlled under-ice oil spill on invertebrates of an arctic and a subarctic stream

    Energy Technology Data Exchange (ETDEWEB)

    Miller, M.C.; Stout, J.R.; Alexander, V.

    1986-01-01

    The short-term drift of macroinvertebrates is documented following two controlled oil spills placed under ice in an arctic (Imnavait Creek) and subarctic (Poker-Caribou Creek) stream just as ice covered the water in early winter. No mortality was observed, but several species responded by differentially drifting from the oil-impacted areas during the following days. In the arctic stream, Trichotanypus posticalis (Diptera) showed a significant increase in drift for the first few days. There was also an overall increase in drift of total organisms post spill. Phaenospectra sp. 1, the numerical dominant, decreased its nocturnal drifting compared with the upstream control station in the 5 days post spill. In the subarctic stream, Skwala sp. 1 (Plecoptera), Prosimulium sp. 1 (Simulidae) and Pseudodiamesa sp. 1 showed significant increase din drift post spill. Among the species of benthic invertebrates sampled with a Hess sampler (WILDCO, Saginaw, Mich.), only the density of Nemoura sp. 1 declined significantly post spill. Polar ordinations using percent difference showed that the oil-treated stations separated from the control stations in both the drift and the Hess bottom samples. Colonization of artificial substrates in Imnavait Creek during the winter following the spill was almost non-existent. In Poker-Caribou Creek much colonization took place over the winter with significantly more occurring on unoiled rocks as compared with oiled rocks.

  10. CO2 and CH4 in sea ice from a subarctic fjord under influence of riverine input

    DEFF Research Database (Denmark)

    Crabeck, O.; Delille, B.; Thomas, D. N.

    2014-01-01

    We present CH4 concentration [CH4] and the partial pressure of CO2 (pCO2) in bulk sea ice from subarctic, land-fast sea ice in the Kapisillit fjord, Greenland. The bulk ice [CH4] ranged from 1.8 to 12.1 nmol L−1, which corresponds to a partial pressure range of 3 to 28 ppmv. This is markedly higher......-saturated compared to the atmosphere (390 ppmv). Our study adds to the few existing studies of CH4 and CO2 in sea ice and concludes that sub-arctic sea can be a sink for atmospheric CO2, while being a net source of CH4. Processes related to the freezing and melting of sea ice represents large unknowns...... to the exchange of CO2 but also CH4. It is therefore imperative to assess the consequences of these unknowns through further field campaigns and targeted research under other sea ice conditions at both hemispheres....

  11. Transformation of leaf litter by insect herbivory in the Subarctic: Consequences for soil biogeochemistry under global change

    Science.gov (United States)

    Kristensen, J. A.; Metcalfe, D. B.; Rousk, J.

    2017-12-01

    Climate warming may increase insect herbivore ranges and outbreak intensities in arctic ecosystems. Thorough understanding of the implications of these changes for ecosystem processes is essential to make accurate predictions of surface-atmosphere carbon (C) feedbacks. Yet, we lack a comprehensive understanding of the impacts of herbivore outbreaks on soil microbial underpinnings of C and nitrogen (N) fluxes. Here, we investigate the growth responses of heterotrophic soil decomposers and C and N mineralisation to simulated defoliator outbreaks in Subarctic birch forests. In microcosms, topsoil was incubated with leaf litter, insect frass, mineral N and combinations of the three; all was added in equal amounts of N. A higher fraction of added C and N was mineralised during outbreaks (frass addition) relative to non-outbreak years (litter addition). However, under high mineral N-availability in the soil of the kind likely under longer periods of enhanced insect herbivory (litter+mineral N), the mineralised fraction of added C decreased while the mineralised fraction of N increased substantially, which suggest a shift towards more N-mining of the organic substrates. This shift was accompanied by higher fungal dominance, and may facilitate soil C-accumulation assuming constant quality of C-inputs. Thus, long-term increases of insect herbivory, of the kind observed in some areas and projected by some models, may facilitate higher ecosystem C-sink capacity in this Subarctic ecosystem.

  12. Effects of climate on organic carbon and the ratio of planktonic to benthic primary producers in a subarctic lake during the past 45 years

    NARCIS (Netherlands)

    Rosén, Peter; Cunningham, Laura; Vonk, Jorien; Karlsson, Jan

    The effects of climatic variables on lake-water total organic carbon (TOC) concentrations and benthic and pelagic primary producers during the past 45 yr were assessed using the sediment records of two subarctic lakes, one with mires and one without mires connected to the lake. The lake with a mire

  13. Effects of elevated CO2, warming and drought episodes on plant carbon uptake in a temperate heath ecosystem are controlled by soil water status

    DEFF Research Database (Denmark)

    Albert, Kristian Rost; Ro-Poulsen, H.; Mikkelsen, Teis Nørgaard

    2011-01-01

    The impact of elevated CO2, periodic drought and warming on photosynthesis and leaf characteristics of the evergreen dwarf shrub Calluna vulgaris in a temperate heath ecosystem was investigated. Photosynthesis was reduced by drought in midsummer and increased by elevated CO2 throughout the growing...... season, whereas warming only stimulated photosynthesis early in the year. At the beginning and end of the growing season, a T × CO2 interaction synergistically stimulated plant carbon uptake in the combination of warming and elevated CO2. At peak drought, the D × CO2 interaction antagonistically down......-regulated photosynthesis, suggesting a limited ability of elevated CO2 to counteract the negative effect of drought. The response of photosynthesis in the full factorial combination (TDCO2) could be explained by the main effect of experimental treatments (T, D, CO2) and the two-factor interactions (D × CO2, T × CO2...

  14. Effects of wind farm construction and operation on mire and wet heath vegetation in the Monte Maior SCI, north-west Spain

    Directory of Open Access Journals (Sweden)

    J. Fagúndez

    2008-07-01

    Full Text Available As part of the environmental impact assessment for the construction of a wind farm within the Monte Maior Natura 2000 Site of Community Importance (SCI in Galicia, north-west Spain, a complete analysis of the development site’s important mire and wet heath plant communities was performed. The study included phytosociological characterisation, species-area metrics, calculation of α and β diversity, and analysis of physiognomical characteristics such as life forms, distribution ranges and phenology. Permanent quadrats were monitored for three years after construction of the wind farm in order to identify and describe any changes in floristic composition. Two phytosociological associations were recognised in mire habitat, namely Eleocharitetum multicaulis (Litorelletea uniflorae and Carici durieui-Sphagnetum papillosi subas. ericetosum mackaianae (Oxycocco-Sphagnetea, whilst the wet heath was assigned to Gentiano pneumonanthe-Ericetum mackaianae (Calluno-Ulicetea. The two plant communities shared most physiognomical characteristics and 13–33% of species. Low values were obtained for α and β diversity, with about nine species per square metre for heathland and ten species per square metre for mire habitat. Hemicryptophytes dominated and no therophytes were recorded. The dominant plant families were Poaceae in heathlands and Cyperaceae in mires, and most of the species flowered in early or late summer. Both communities were stable and no change in any of the attributes investigated was observed during the study period. The results indicate that, so long as the traditional land use of low-intensity grazing can be maintained, there are no major hazards for these plant communities. However, some of the data suggest that the improvement of access to the area provided by the wind farm may result in an increase in human activity which could affect environmental conditions and thus the longer-term stability of the plant communities.

  15. [Impact of industrial pollution on emission of carbon dioxide by soils in the Kola Subarctic Region].

    Science.gov (United States)

    Koptsik, G N; Kadulin, M S; Zakharova, A I

    2015-01-01

    Soil emission of carbon dioxide, the key component of carbon cycle and the characteristic of soil biological activity, has been studied in background and polluted ecosystems in the Kola subarctic, the large industrial region of Russia. Long-term air pollution by emissions of "Pechenganikel" smelter, the largest source of sulphur dioxide and heavy metals in Northern Europe, has caused the technogenic digression of forest ecosystems. As a result of the digression, the tree layer was destructed, the number of plant species was diminished, the activity of soil biota was weakened, the soils were polluted and exhausted, biogeochemical cycles of elements were disturbed and productivity of ecosystems shrunk. Field investigations revealed the decrease of the in.situ soil respiration in average from 190-230 mg C-CO2/m2 x per h in background pine forests to 130-160, 100, and 20 mg C-CO2/m2.per h at the stages of pine defoliation, sparse pine forest and technogenic barrens of the technogenic succession, respectively. The soil respira- tion in birch forests was more intense than in pine forests and tended to decrease from about 290 mg C-CO2/m2 x per h in background forests to 210-220 and 170-190 mg C-CO2/m2 x per h in defoliating forests and technogenic sparse forests, respectively. Due to high spatial variability of soil respiration in both pine and birch forests significant differences from the background level were found only in technogenic sparse forests and barrens. Soil respiration represents total production of carbon dioxide by plant roots and soil microorganisms. The decrease in share of root respiration in the total soil respiration with the rise of pollution from 38-57% in background forests up to zero in technogenic barrens has been revealed for the first time for this region. This indicates that plants seem to be more sensitive to pollution as compared to relatively resistant microorganisms. Soil respiration and the contribution of roots to the total respiration

  16. Greenhouse gas emissions related to landscape elements in the subarctic environment at Churchill, Manitoba

    International Nuclear Information System (INIS)

    Churchill, J.; Tenuta, M.; Bello, R.; Papakyriakou, T.

    2006-01-01

    The relationship between greenhouse gas (GHG) emissions, landscape elements and major environmental regulators was studied. The hydrologic regimes of the Hudson Bay Lowlands are expected to change along with the extent of permafrost and composition of vegetation due to increased levels of GHGs associated with global warming. Two transects were created at a Polygonized-Peat Plateau (PPP) and a Spruce Forest (SF) site in 2005. A sub-set on 4 dominant landscape elements of each transect were used to estimate emissions of carbon dioxide (CO 2 ), methane (CH 4 ), and nitric oxide (N 2 O) on a weekly basis from June to August. In order to obtain a good sampling representation of environmental conditions and of the gradients in plant communities, the entire transect at PPP was sampled monthly. In order to examine the role of soil conditions on the production and consumption of GHG leading to surface fluxes, soil gas samplers were installed at 2 depths at both sites. N 2 O production and consumption were found to be inconsequential at both sites. However, high methane emissions were observed when the volumetric moisture content (VMC) rose higher than 80 per cent at the edge of the ponds. Methane consumption was found to be related to low VMC values (20-40 per cent) for the tops of peat polygons. Soil atmosphere concentrations for CO 2 and CH 4 at PPP were typically much higher at depths of 23-32 cm compared to depths of 5-9 cm. Some of the wettest landscape elements had very high CH 4 content, but had no corresponding CH 4 flux from the soil surface, suggesting that the gas was consumed under aerobic conditions at the soil surface. It was concluded that GHG emissions from both sites were altered by both landscape elements and environmental regulators such as temperature and moisture. Future work will focus on identifying the association of these relationships to processes responsible for GHG emissions in subarctic environments. The impact of global warming on these

  17. Using 67Cu to study the biogeochemical cycling of copper in the northeast subarctic Pacific Ocean

    Directory of Open Access Journals (Sweden)

    David M Semeniuk

    2016-06-01

    Full Text Available Microbial copper (Cu nutrition and dissolved Cu speciation were surveyed along Line P, a coastal to open ocean transect that extends from the coast of British Columbia, Canada, to the high-nutrient-low-chlorophyll (HNLC zone of the northeast subarctic Pacific Ocean. Steady-state size fractionated Cu uptake rates and Cu:C assimilation ratios were determined at in situ Cu concentrations and speciation using a 67Cu tracer method. The cellular Cu:C ratios that we measured (~30 µmol Cu mol C-1 are similar to recent estimates using synchrotron x-ray fluorescence (SXRF, suggesting that the 67Cu method can determine in situ metabolic Cu demands. We examined how environmental changes along the Line P transect influenced Cu metabolism in the sub-microplankton community. Cellular Cu:C assimilation ratios and uptake rates were compared with net primary productivity, bacterial abundance and productivity, total dissolved Cu, Cu speciation, and a suite of other chemical and biological parameters. Total dissolved Cu concentrations ([Cu]d were within a narrow range (1.46 to 2.79 nM, and Cu was bound to a ~5-fold excess of strong ligands with conditional stability constants ( of ~1014. Free Cu2+ concentrations were low (pCu 14.4 to 15.1, and total and size fractionated net primary productivity (NPPV; µg C L-1 d-1 were negatively correlated with inorganic Cu concentrations ([Cu′]. We suggest this is due to greater Cu′ drawdown by faster growing phytoplankton populations. Using the relationship between [Cu′] drawdown and NPPV, we calculated a regional photosynthetic Cu:C drawdown export ratio between 1.5 and 15 µmol Cu mol C-1, and a mixed layer residence time (2.5 to 8 years that is similar to other independent estimates (2-12 years. Total particulate Cu uptake rates were between 22 and 125 times faster than estimates of Cu export; this is possibly mediated by rapid cellular Cu uptake and efflux by phytoplankton and bacteria or the effects of grazers and

  18. Differentiating TOC sources, preservation, and potential methane emissions in sub-Arctic lakes in Sweden

    Science.gov (United States)

    Johnson, J. E.; Varner, R. K.; Wik, M.; Chanton, J.; Crill, P. M.

    2015-12-01

    Organic carbon-rich sediments from high latitude, shallow lakes and ponds are significant sources of methane throughout the Arctic. The origin and evolution of these lakes and ponds, however, is often not the same. Several lake types have been identified based on (1) hydrological conditions (melt-water fed, rain water fed, groundwater influenced, evaporation dominated, drained) (2) permafrost condition (thermokarst), and (3) time of origin (glacial or post-glacial). Given sufficient time (100's to 1000's years) many of these lake types may morph into others. In sub-Arctic Sweden, near Abisko and within the zone of discontinuous permafrost, the elongate glacial lake Torneträsk is fed by several streams draining the surrounding highlands. Lake Tornetrask is one of several NW-SE trending glacial lakes common in the landscape throughout northern and western Sweden. Between and alongside these glacial lakes, several small (ponds exist in low-lying mires. Sediment cores from the lakes in the Stordalen Mire are characterized by high total organic carbon (TOC) content (10-50 wt. %) in the uppermost ~50 cm and commonly underlain by glaciofluvial derived sediments with lower TOC (emissions from several of these lakes has also been measured and is driven by heat input. Coincident young ages of carbon in the sediments and in methane indicate in situ production. A published record from Lake Torneträsk shows sediments there contain significantly less TOC (1-2.5 wt. %) that is derived primarily from old, terrestrial organic carbon delivered via rivers to the lake. Although the larger and deeper glacial lakes currently occupy much of the landscape it is becoming clear that as the Arctic warms TOC preservation and methane production in the smaller lakes and ponds play a more significant, immediate role in emission of methane to the atmosphere. With continued warming in the Arctic, terrestrial TOC will be relinquished from highland watersheds to glacial lakes, but the methane

  19. Response Characteristics of Dissolved Organic Carbon Flushing in a Subarctic Alpine Catchment

    Science.gov (United States)

    Carey, S. K.

    2002-12-01

    Dissolved organic carbon (DOC) is an important part of ecosystem-scale carbon balances and in the transport of contaminants as it interacts with other dissolved substances including trace metals. It also can be used as a surrogate hydrological tracer in permafrost regions as near-surface waters are often DOC enriched due to the presence of thick organic soils. In a small subarctic alpine catchment within the Wolf Creek Research Basin, Yukon, Canada, DOC was studied in the summer of 2001 and spring of 2002 to determine the role frost (both permanent and seasonal), snowmelt and summer storms on DOC flushing. Peak DOC concentrations occurred during the snowmelt period, approximately one week prior to peak discharge. However, peak discharge took place several weeks after snow on south facing exposures had melted. Within the hillslopes, DOC concentrations were three to five times greater in wells underlain with permafrost compared with seasonal frost. Groundwater DOC concentrations declined during snowmelt, yet remained at levels above the streamflow. After peaking, streamflow DOC concentrations declined exponentially suggesting a simple flushing mechanism, however there did not appear to be a relation between DOC and topographic position. Following melt, permafrost underlain slopes had near-surface water tables and retained elevated levels of DOC, whereas slopes without permafrost had rapidly declining water tables at upslope locations with low DOC concentrations at all positions except near-stream riparian zones. The influence of summer rainstorms on DOC was monitored on three occasions. In each case DOC peaked on the ascending limb of the runoff hydrograph and declined exponentially on the receding limb and hysteretic behavior occurred between discharge and DOC during all events. Patterns of DOC within the hillslopes and streams suggest that runoff from permafrost-underlain slopes control DOC flushing within the stream during both snowmelt and summer periods. This

  20. Growing season boundary layer climate and surface exchanges in a subarctic lichen woodland

    Science.gov (United States)

    Fitzjarrald, David R.; Moore, Kathleen E.

    1994-01-01

    Between June and August 1990, observations were made at two surface micrometeorological towers near Schefferville Quebec (54 deg 52 min N, 66 deg 40.5 min W), one in a fen and one in the subarctic lichen woodland, and at four surface climatological stations. Data from these surface stations were supplemented by regular radiosonde launches. Supporting measurements of radiative components and soil temperatures allowed heat and moisture balances to be obtained at two sites. The overall surface meteorological experiment design and results of micrometeorological observations made on a 30-m tower in the lichen woodland are presented here. Seasonal variation in the heat and water vapor transport characteristics illustrate the marked effect of the late summer climatological shift in air mass type. During the first half of the summer, average valley sidewalls only 100 m high are sufficient to channel winds along the valley in the entire convective boundary layer. Channeling effects at the surface, known for some time at the long-term climate station in Schefferville, are observed both at ridge top and in the valley, possibly the response of the flow to the NW-SE orientation of valleys in the region. Diurnal surface temperature amplitude at ridge top (approximately equal to 10 C) was found to be half that observed in the valley. Relatively large differences in precipitation among these stations and the climatological station at Schefferville airport were observed and attributed to the local topography. Eddy correlation observations of the heat, moisture and momentum transports were obtained from a 30-m tower above a sparse (approximately equal to 616 stems/ha) black spruce lichen woodland. Properties of the turbulent surface boundary layer agree well with previous wind tunnel studies over idealized rough surfaces. Daytime Bowen ratios of 2.5-3 are larger than those reported in previous studies. Surface layer flux data quality was assessed by looking at the surface layer heat

  1. Parallel structure among environmental gradients and three trophic levels in a subarctic estuary

    Science.gov (United States)

    Speckman, Suzann G.; Piatt, John F.; Minte-Vera, Carolina V.; Parrish, Julia K.

    2005-07-01

    We assessed spatial and temporal variability in the physical environment of a subarctic estuary, and examined concurrent patterns of chlorophyll α abundance (fluorescence), and zooplankton and forage fish community structure. Surveys were conducted in lower Cook Inlet, Alaska, during late July and early August from 1997 through 1999. Principle components analysis (PCA) revealed that spatial heterogeneity in the physical oceanographic environment of lower Cook Inlet could be modeled as three marine-estuarine gradients characterized by temperature, salinity, bottom depth, and turbidity. The gradients persisted from 1997 through 1999, and PCA explained 68% to 92% of the variance in physical oceanography for each gradient-year combination. Correlations between chlorophyll α abundance and distribution and the PCA axes were weak. Chlorophyll was reduced by turbidity, and low levels occurred in areas with high levels of suspended sediments. Detrended correspondence analysis (DCA) was used to order the sample sites based on species composition and to order the zooplankton and forage fish taxa based on similarities among sample sites for each gradient-year. Correlations between the structure of the physical environment (PCA axis 1) and zooplankton community structure (DCA axis 1) were strong ( r = 0.43-0.86) in all years for the three marine-estuarine gradients, suggesting that zooplankton community composition was structured by the physical environment. The physical environment (PCA) and forage fish community structure (DCA) were weakly correlated in all years along Gradient 2, defined by halocline intensity and surface temperature and salinity, even though these physical variables were more important for defining zooplankton habitats. However, the physical environment (PCA) and forage fish community structure (DCA) were strongly correlated along the primary marine-estuarine gradient (#1) in 1997 ( r = 0.87) and 1998 ( r = 0.82). The correlation was poor ( r = 0.32) in

  2. Application of global datasets for hydrological modelling of a remote, snowmelt driven catchment in the Canadian Sub-Arctic

    Science.gov (United States)

    Casson, David; Werner, Micha; Weerts, Albrecht; Schellekens, Jaap; Solomatine, Dimitri

    2017-04-01

    Hydrological modelling in the Canadian Sub-Arctic is hindered by the limited spatial and temporal coverage of local meteorological data. Local watershed modelling often relies on data from a sparse network of meteorological stations with a rough density of 3 active stations per 100,000 km2. Global datasets hold great promise for application due to more comprehensive spatial and extended temporal coverage. A key objective of this study is to demonstrate the application of global datasets and data assimilation techniques for hydrological modelling of a data sparse, Sub-Arctic watershed. Application of available datasets and modelling techniques is currently limited in practice due to a lack of local capacity and understanding of available tools. Due to the importance of snow processes in the region, this study also aims to evaluate the performance of global SWE products for snowpack modelling. The Snare Watershed is a 13,300 km2 snowmelt driven sub-basin of the Mackenzie River Basin, Northwest Territories, Canada. The Snare watershed is data sparse in terms of meteorological data, but is well gauged with consistent discharge records since the late 1970s. End of winter snowpack surveys have been conducted every year from 1978-present. The application of global re-analysis datasets from the EU FP7 eartH2Observe project are investigated in this study. Precipitation data are taken from Multi-Source Weighted-Ensemble Precipitation (MSWEP) and temperature data from Watch Forcing Data applied to European Reanalysis (ERA)-Interim data (WFDEI). GlobSnow-2 is a global Snow Water Equivalent (SWE) measurement product funded by the European Space Agency (ESA) and is also evaluated over the local watershed. Downscaled precipitation, temperature and potential evaporation datasets are used as forcing data in a distributed version of the HBV model implemented in the WFLOW framework. Results demonstrate the successful application of global datasets in local watershed modelling, but

  3. Experimentally increased nutrient availability at the permafrost thaw front selectively enhances biomass production of deep-rooting subarctic peatland species.

    Science.gov (United States)

    Keuper, Frida; Dorrepaal, Ellen; van Bodegom, Peter M; van Logtestijn, Richard; Venhuizen, Gemma; van Hal, Jurgen; Aerts, Rien

    2017-10-01

    Climate warming increases nitrogen (N) mineralization in superficial soil layers (the dominant rooting zone) of subarctic peatlands. Thawing and subsequent mineralization of permafrost increases plant-available N around the thaw-front. Because plant production in these peatlands is N-limited, such changes may substantially affect net primary production and species composition. We aimed to identify the potential impact of increased N-availability due to permafrost thawing on subarctic peatland plant production and species performance, relative to the impact of increased N-availability in superficial organic layers. Therefore, we investigated whether plant roots are present at the thaw-front (45 cm depth) and whether N-uptake ( 15 N-tracer) at the thaw-front occurs during maximum thaw-depth, coinciding with the end of the growing season. Moreover, we performed a unique 3-year belowground fertilization experiment with fully factorial combinations of deep- (thaw-front) and shallow-fertilization (10 cm depth) and controls. We found that certain species are present with roots at the thaw-front (Rubus chamaemorus) and have the capacity (R. chamaemorus, Eriophorum vaginatum) for N-uptake from the thaw-front between autumn and spring when aboveground tissue is largely senescent. In response to 3-year shallow-belowground fertilization (S) both shallow- (Empetrum hermaphroditum) and deep-rooting species increased aboveground biomass and N-content, but only deep-rooting species responded positively to enhanced nutrient supply at the thaw-front (D). Moreover, the effects of shallow-fertilization and thaw-front fertilization on aboveground biomass production of the deep-rooting species were similar in magnitude (S: 71%; D: 111% increase compared to control) and additive (S + D: 181% increase). Our results show that plant-available N released from thawing permafrost can form a thus far overlooked additional N-source for deep-rooting subarctic plant species and increase their

  4. Examining the relationship between mercury and organic matter in lake sediments along a latitudinal transect in subarctic Canada

    Science.gov (United States)

    Galloway, Jennifer M.; Sanei, Hamed; Parsons, Michael; Swindles, Graeme T.; Macumber, Andrew L.; Patterson, R. Timothy; Palmer, Michael; Falck, Hendrik

    2016-04-01

    The accumulation of Hg in aquatic environments at both high and low latitudes can be controlled by organic matter through algal scavenging, thus complicating the interpretation of historical Hg profiles in lake sediments1,2,3. However, other recent studies suggest that algal scavenging is not important in governing Hg flux to sediments4, in some cases because of dilution by inorganic materials5. This study examines relationships between Hg and organic matter (OM) in over 100 lakes located between 60.5 and 65.4 °N and crossing the latitudinal tree-line in subarctic Canada. The latitudinal gradient approach in our study offers an opportunity to better understand climate and environmental controls on OM accumulation and its role in influencing Hg deposition in subarctic lacustrine environments. We used Rock Eval 6 pyrolysis to determine total organic carbon (TOC%), S1 (soluble OM consisting of degradable lipids and algal pigments), S2 (OM derived from highly aliphatic biomacromolecule structure of algal cell walls), and S3 (OM dominated by carbohydrates, lignins, and plant materials). Total Hg in sediments was measured using thermal decomposition, amalgamation, and atomic absorption spectrophotometry. In these lake sediments, S2 composes the majority of TOC (Pearson's r = 0.978, porganic matter and mercury in recent lake sediment: the physical-geochemical aspects. Appl Geochem 21: 1900-12. 2Outridge, P.M., Sanei, H., Stern, G.A., Hamilton, P.B., Goodarzi, F. 2007. Evidence for control of mercury accumulation rates in Canadian high Arctic lake sediments by variations of aquatic primary productivity. Environ Sci Technol 41: 5259-65. 3Wu, F., Zu, L., Liao, H., Guo, F., Zhao, X., Giesy, J. 2013. Relationship between mercury and organic carbon in sediment cores from Lakes Qinghai and Chenghai, China. J Soils Sediments 13: 1084-1092.4Kirk, J.L., Muir, D.C.G., Antoniades, D., Douglas, M.S.V., Evans, M.S., Jackson, T.A., Kling, H., Lamoureux, S., Lim, D.S.S., Pienitz, R

  5. Short-term variability in bacterial abundance, cell properties, and incorporation of leucine and thymidine in subarctic sea ice

    DEFF Research Database (Denmark)

    Kaartokallio, H.; Sogaard, D. H.; Norman, L.

    2013-01-01

    Sea ice is a biome of immense size and provides a range of habitats for diverse microbial communities, many of which are adapted to living at low temperatures and high salinities in brines. We measured simultaneous incorporation of thymidine (TdR) and leucine (Leu), bacterial cell abundance...... and cell population properties (by flow cytometry) in subarctic sea ice in SW Greenland. Short-term temporal variability was moderate, and steep environmental gradients, typical for sea ice, were the main drivers of the variability in bacterial cell properties and activity. Low nucleic acid (LNA) bacteria...... and marine biofilm systems. Leu: TdR ratios were high (up to >300) in lowermost ice layers, and when compared to published respiration measurements, these results suggest non-specific Leu incorporation. There was evidence of polyhydroxyalkanoate (PHA)-containing bacteria in the sea ice, shown by brightly...

  6. Phytoplankton growth and microzooplankton grazing along a sub-Arctic fjord (Godthåbsfjord, West Greenland)

    DEFF Research Database (Denmark)

    Calbet, A.; Riisgaard, Karen; Saiz, E.

    2011-01-01

    the nutrient rich waters in the upwelling area in the vicinity of the glacier. Most of the grazing impact was on the 20 µm microzooplankton, as deducted from additional dilution experiments removing > 20 µm. Overall, little......We evaluated the role of microzooplankton (sensu latto, grazers sea transect in the Greenland subarctic fjord, Godthåbfjord. Based on the distribution of size fractionated chlorophyll a (chl a) concentrations...... we established four zones: i) Fyllas Bank, characterized by deep chl a maxima (ca. 30-40 m) consisting of large cells; ii) the mouth and main branch of the fjord, where phytoplankton was relatively homogeneously distributed in the upper 30 m layer; iii) inner waters influenced by glacial melt water...

  7. Comparisons between POC and zooplankton swimmer flux from sediment traps in the subarctic and subtropical North Pacific

    Science.gov (United States)

    Yokoi, Naoya; Abe, Yoshiyuki; Kitamura, Minoru; Honda, Makio C.; Yamaguchi, Atsushi

    2018-03-01

    Seasonal changes in zooplankton swimmer (ZS) abundance, biomass and community structure were evaluated based on samples collected by moored sediment traps at a depth of 200 m in the subarctic (SA) and subtropical (ST) western North Pacific. Based on these samples, we made comparisons on two topics: 1) latitudinal (subarctic vs. subtropical) changes in ZS abundance, biomass and community and 2) quantitative differences between the ZS and particle organic carbon (POC) fluxes based on data from moored or drifting sediment traps. The results showed that the ZS flux was greater in the SA (annual mean: 311 ind. m-2 day-1 or 258 mg C m-2 day-1) than in the ST (135 ind. m-2 day-1 or 38 mg C m-2 day-1). The peak ZS flux was observed from July-August in the SA and from April-May in the ST. The dominant taxa were Copepoda and Chaetognatha in the SA and Ostracoda and Mollusca in the ST. These latitudinal differences are likely related to the dominance of large-sized Copepoda in the SA, regional differences in the timing of the spring phytoplankton bloom, and the magnitude and size structure of primary producers. The percent composition of ZS to the total C flux (= ZS+POC flux) varied by region: 85-95% in the SA and 47-75% in the ST. These differences between the ZS composition and the total C flux are most likely caused by the dominance of large-sized Copepoda (Neocalanus spp. and Eucalanus bungii) in the SA.

  8. Petroleum hydrocarbon biodegradation under seasonal freeze-thaw soil temperature regimes in contaminated soils from a sub-Arctic site.

    Science.gov (United States)

    Chang, Wonjae; Klemm, Sara; Beaulieu, Chantale; Hawari, Jalal; Whyte, Lyle; Ghoshal, Subhasis

    2011-02-01

    Several studies have shown that biostimulation in ex situ systems such as landfarms and biopiles can facilitate remediation of petroleum hydrocarbon contaminated soils at sub-Arctic sites during summers when temperatures are above freezing. In this study, we examine the biodegradation of semivolatile (F2: C10-C16) and nonvolatile (F3: C16-C34) petroleum hydrocarbons and microbial respiration and population dynamics at post- and presummer temperatures ranging from -5 to 14 °C. The studies were conducted in pilot-scale tanks with soils obtained from a historically contaminated sub-Arctic site in Resolution Island (RI), Canada. In aerobic, nutrient-amended, unsaturated soils, the F2 hydrocarbons decreased by 32% during the seasonal freeze-thaw phase where soils were cooled from 2 to -5 °C at a freezing rate of -0.12 °C d(-1) and then thawed from -5 to 4 °C at a thawing rate of +0.16 °C d(-1). In the unamended (control) tank, the F2 fraction only decreased by 14% during the same period. Biodegradation of individual hydrocarbon compounds in the nutrient-amended soils was also confirmed by comparing their abundance over time to that of the conserved diesel biomarker, bicyclic sesquiterpanes (BS). During this period, microbial respiration was observed, even at subzero temperatures when unfrozen liquid water was detected during the freeze-thaw period. An increase in culturable heterotrophs and 16S rDNA copy numbers was noted during the freezing phase, and the (14)C-hexadecane mineralization in soil samples obtained from the nutrient-amended tank steadily increased. Hydrocarbon degrading bacterial populations identified as Corynebacterineae- and Alkanindiges-related strains emerged during the freezing and thawing phases, respectively, indicating there were temperature-based microbial community shifts.

  9. Mesoscale dynamics in the Lofoten Basin - a sub-Arctic "hot spot" of oceanic variability

    Science.gov (United States)

    Volkov, D. L.; Belonenko, T. V.; Foux, V. R.

    2012-12-01

    A sub-Arctic "hot spot" of intense mesoscale variability is observed in the Lofoten Basin (LB) - a topographic depression with a maximum depth of about 3250 m, located in the Norwegian Sea. The standard deviation of sea surface height (SSH), measured with satellite altimetry, reaches nearly 15 cm in the center of the basin (Figure 1a). Using a space-time lagged correlation analysis of altimetry data, we discover a cyclonic propagation of the mesoscale SSH anomalies around the center of the LB with time-averaged phase speeds of 2-4 km/day, strongly linked to bottom topography (Figure 1c). The fact that surface drifter trajectories do not exhibit cyclonic circulation in the LB (Figure 1b) suggests that, at least in the upper ocean, satellite altimetry observes only the propagation of form without the corresponding transfer of mass. Linearly propagating wavelike disturbances that do not trap fluid inside are related to planetary or Rossby waves. Variations in topography may lead to the concentration of wave energy in certain regions or wave trapping. The dispersion analysis suggests that the observed wavelike cyclonic propagation of SSH anomalies in the LB is the manifestation of baroclinic topographic Rossby waves, that we term "the basin waves" in order to distinguish them from the other types of topographic waves, such as shelf or trench waves. We identify two modes of basin waves in the LB: a di-pole mode and a quadri-pole mode. The wavelength of each mode is about 500 km. The frequency of these modes is not constant and the phase speed varies from about 2 to 8 km/day. We show that the cyclonically rotating basin waves are responsible for the observed amplification of SSH variability in the LB. Because the baroclinic basin waves in the LB are probably associated with large vertical displacements of the thermocline and due to possible wave breaking events, they can play an important role in the mixing of the inflowing Atlantic Water with ambient water masses

  10. Decadal Variations of the Western Subarctic Gyre and Main Pycnocline Depth due to Wind Stress Change in the Northern North Pacific

    Science.gov (United States)

    Nagano, A.; Wakita, M.

    2017-12-01

    From the late 1990s to the early 2000s, the western subarctic gyre of the North Pacific, a cyclonic circulation in the western subarctic region, shrank northward associated with a decadal increase of sea surface height (SSH). This gyre change displaced the main pycnocline (halocline) downward and is expected to contribute to the deepening of the overlying temperature minimum layer. This is considered to affect the biogeochemical conditions in the western subarctic region, where is known as substantially slow ocean acidification region. In this study, on the basis of wind stress field data in the subpolar region (40˚N—54˚N, 160˚E—135˚W) during 1979—2014 provided by U.S. National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis, we estimated the variation in SSH, solving the vorticity gradient equation on the beta plane. Decadal increase in SSH at Station K2 (47˚N, 160˚E), representative point of the western subarctic region, was well produced by the calculation, and the correlation coefficient with altimetric SSH exceeds 0.6. The calculated SSH variation consists of the variations due to the barotropic and baroclinic Rossby wave modes. The gyre shrinkage is found to be caused primarily by the barotropic response to the wind change in the whole subpolar region and secondary by the first baroclinic response. Meanwhile, the decadal deepening of the main pycnocline at K2 is attributed to the baroclinic responses of the higher (second, third, and fourth) vertical modes to the local wind change.

  11. Oxygen and silicon stable isotopes of diatom silica. Reconstructing changes in surface water hydrography and silicic acid utilization in the late Pleistocene subarctic Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Maier, Edith

    2014-03-05

    Deglacial variations in upper ocean nutrient dynamics and stratification in high latitudes, as well as associated changes in thermohaline overturning circulation, are thought to have played a key role in changing atmospheric CO{sub 2} concentrations. This thesis examines the relationship between past changes in subarctic Pacific upper ocean stratification and nutrient (silicic acid) utilization, using oxygen and silicon stable isotopes of diatom silica, for the first time at millennial-scale resolution and analyzed with a new and efficient instrumentation set-up. The isotopic data, presented in three manuscripts, show a consistent picture of millennial-scale variability in upper ocean stratification and silicic acid utilization during the last ∝50 ka BP, e.g. indicating that the subarctic Pacific was a source region for atmospheric CO{sub 2} during the last deglaciation (late Heinrich Stadial 1 and the Boelling/Alleroed). The presented results demonstrate the high potential of combined diatom oxygen and silicon stable isotope analysis especially for, but not restricted to, marine regions characterized by a low biogenic carbonate content like the subarctic Pacific and the Southern Ocean.

  12. Oxygen and silicon stable isotopes of diatom silica. Reconstructing changes in surface water hydrography and silicic acid utilization in the late Pleistocene subarctic Pacific

    International Nuclear Information System (INIS)

    Maier, Edith

    2014-01-01

    Deglacial variations in upper ocean nutrient dynamics and stratification in high latitudes, as well as associated changes in thermohaline overturning circulation, are thought to have played a key role in changing atmospheric CO 2 concentrations. This thesis examines the relationship between past changes in subarctic Pacific upper ocean stratification and nutrient (silicic acid) utilization, using oxygen and silicon stable isotopes of diatom silica, for the first time at millennial-scale resolution and analyzed with a new and efficient instrumentation set-up. The isotopic data, presented in three manuscripts, show a consistent picture of millennial-scale variability in upper ocean stratification and silicic acid utilization during the last ∝50 ka BP, e.g. indicating that the subarctic Pacific was a source region for atmospheric CO 2 during the last deglaciation (late Heinrich Stadial 1 and the Boelling/Alleroed). The presented results demonstrate the high potential of combined diatom oxygen and silicon stable isotope analysis especially for, but not restricted to, marine regions characterized by a low biogenic carbonate content like the subarctic Pacific and the Southern Ocean.

  13. Region effects influence local tree species diversity.

    Science.gov (United States)

    Ricklefs, Robert E; He, Fangliang

    2016-01-19

    Global patterns of biodiversity reflect both regional and local processes, but the relative importance of local ecological limits to species coexistence, as influenced by the physical environment, in contrast to regional processes including species production, dispersal, and extinction, is poorly understood. Failure to distinguish regional influences from local effects has been due, in part, to sampling limitations at small scales, environmental heterogeneity within local or regional samples, and incomplete geographic sampling of species. Here, we use a global dataset comprising 47 forest plots to demonstrate significant region effects on diversity, beyond the influence of local climate, which together explain more than 92% of the global variation in local forest tree species richness. Significant region effects imply that large-scale processes shaping the regional diversity of forest trees exert influence down to the local scale, where they interact with local processes to determine the number of coexisting species.

  14. Equilibrium Bird Species Diversity in Atlantic Islands.

    Science.gov (United States)

    Valente, Luis; Illera, Juan Carlos; Havenstein, Katja; Pallien, Tamara; Etienne, Rampal S; Tiedemann, Ralph

    2017-06-05

    Half a century ago, MacArthur and Wilson proposed that the number of species on islands tends toward a dynamic equilibrium diversity around which species richness fluctuates [1]. The current prevailing view in island biogeography accepts the fundamentals of MacArthur and Wilson's theory [2] but questions whether their prediction of equilibrium can be fulfilled over evolutionary timescales, given the unpredictable and ever-changing nature of island geological and biotic features [3-7]. Here we conduct a complete molecular phylogenetic survey of the terrestrial bird species from four oceanic archipelagos that make up the diverse Macaronesian bioregion-the Azores, the Canary Islands, Cape Verde, and Madeira [8, 9]. We estimate the times at which birds colonized and speciated in the four archipelagos, including many previously unsampled endemic and non-endemic taxa and their closest continental relatives. We develop and fit a new multi-archipelago dynamic stochastic model to these data, explicitly incorporating information from 91 taxa, both extant and extinct. Remarkably, we find that all four archipelagos have independently achieved and maintained a dynamic equilibrium over millions of years. Biogeographical rates are homogeneous across archipelagos, except for the Canary Islands, which exhibit higher speciation and colonization. Our finding that the avian communities of the four Macaronesian archipelagos display an equilibrium diversity pattern indicates that a diversity plateau may be rapidly achieved on islands where rates of in situ radiation are low and extinction is high. This study reveals that equilibrium processes may be more prevalent than recently proposed, supporting MacArthur and Wilson's 50-year-old theory. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Elemental composition and optical properties reveal changes in dissolved organic matter along a permafrost thaw chronosequence in a subarctic peatland

    Energy Technology Data Exchange (ETDEWEB)

    Hodgkins, Suzanne; Tfaily, Malak M.; Podgorski, David C.; McCalley, Carmody; Saleska, Scott; Crill, Patrick M.; Rich, Virginia; Chanton, Jeffrey; Cooper, William T.

    2016-08-01

    The fate of carbon stored in permafrost-zone peatlands represents a significant uncertainty in global climate modeling. Given that the breakdown of dissolved organic matter (DOM) is often a major pathway for decomposition in peatlands, knowledge of DOM reactivity under different permafrost regimes is critical for determining future climate feedbacks. To explore the effects of permafrost thaw and resultant plant succession on DOM reactivity, we used a combination of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), UV/Vis absorbance, and excitation-emission matrix spectroscopy (EEMS) to examine the DOM elemental composition and optical properties of 27 pore water samples gathered from various sites along a permafrost thaw sequence in Stordalen Mire, a thawing subarctic peatland in northern Sweden. The presence of dense Sphagnum moss, a feature that is dominant in the intermediate thaw stages, appeared to be the main driver of variation in DOM elemental composition and optical properties at Stordalen. Specifically, DOM from sites with Sphagnum had greater aromaticity, higher average molecular weights, and greater O/C, consistent with a higher abundance of phenolic compounds that likely inhibit decomposition. These compounds are released by Sphagnum and may accumulate due to inhibition of phenol oxidase activity by the acidic pH at these sites. In contrast, sites without Sphagnum, specifically fully-thawed rich fens, had more saturated, more reduced compounds, which were high in N and S. Optical properties at rich fens were indicated the presence of microbially-derived DOM, consistent with the higher decomposition rates previously measured at these sites. These results indicate that Sphagnum acts as an inhibitor of rapid decomposition and CH4 release in thawing subarctic peatlands, consistent with lower rates of CO2 and CH4 production previously observed at these sites. However, this inhibitory effect may disappear if Sphagnumdominated bogs

  16. Comparison of snow melt properties across multiple spatial scales and landscape units in interior sub-Arctic boreal Alaskan watersheds

    Science.gov (United States)

    Bennett, K. E.; Cherry, J. E.; Hiemstra, C. A.; Bolton, W. R.

    2013-12-01

    Interior sub-Arctic Alaskan snow cover is rapidly changing and requires further study for correct parameterization in physically based models. This project undertook field studies during the 2013 snow melt season to capture snow depth, snow temperature profiles, and snow cover extent to compare with observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor at four different sites underlain by discontinuous permafrost. The 2013 melt season, which turned out to be the latest snow melt period on record, was monitored using manual field measurements (SWE, snow depth data collection), iButtons to record temperature of the snow pack, GoPro cameras to capture time lapse of the snow melt, and low level orthoimagery collected at ~1500 m using a Navion L17a plane mounted with a Nikon D3s camera. Sites were selected across a range of landscape conditions, including a north facing black spruce hill slope, a south facing birch forest, an open tundra site, and a high alpine meadow. Initial results from the adjacent north and south facing sites indicate a highly sensitive system where snow cover melts over just a few days, illustrating the importance of high resolution temporal data capture at these locations. Field observations, iButtons and GoPro cameras show that the MODIS data captures the melt conditions at the south and the north site with accuracy (2.5% and 6.5% snow cover fraction present on date of melt, respectively), but MODIS data for the north site is less variable around the melt period, owing to open conditions and sparse tree cover. However, due to the rapid melt rate trajectory, shifting the melt date estimate by a day results in a doubling of the snow cover fraction estimate observed by MODIS. This information can assist in approximating uncertainty associated with remote sensing data that is being used to populate hydrologic and snow models (the Sacramento Soil Moisture Accounting model, coupled with SNOW-17, and the Variable

  17. The impact of enhanced ultraviolet-B radiation on litter quality and decomposition processes in Vaccinium leaves from the Subarctic

    Energy Technology Data Exchange (ETDEWEB)

    Gehrke, C [Lund Univ., Dept. of Plant Ecology, Lund (Sweden); Johanson, U [Lund Univ., Dept. of Plant Physiology, Lund (Sweden); Callaghan, T V; Chadwick, D; Robinson, C H [Merlewood Research Station, Inst. of Terrestrial Ecology, Cumbira (United Kingdom)

    1995-05-01

    The aim of this study was to investigate how UV-B radiation will affect (1) the quality of plant litter grown under differente UV-B levels in the Subarctic and (2) decomposition under different UV-B levels. The deciduous dwarf shrubs Vaccinium uliginosum and V. myrtillus grew under ambient and enchanced UV-B (corresponding to 15% ozone depletion) in a natural health ecosystem in the Subarctic. After two growing seasons senesced leaves were collected and decomposed in a 2 x 2 factorial experiment under both laboratory conditions for 62 d (V. uliginosum: no UV-B and 10 kJ m{sup -2} d{sup -1} UV-B{sub BE}) and under field conditions for twelve months (V. myrtillus: ambient and enhanced UV-B corresponding 15% ozone depletion). Additionally, colonization and growth of decomposing fungi were studied on leaves decomposed without and with UV-B in the laboratory. The enhanced UV-B during growth changed the litter quality (decrease in {alpha}-cellulose, increase in tannins). Subsequently the microbial respiration was decreased. This and the decreased cellulose/lignin ratio may have led to the lower relative mass loss due to treatments as detected both after 62 d decomposition in the laboratory and after twelve months decompositon in the field. The UV-B during decomposition decreased the proportion of lignin in the plant residues, which is possibly due to photodegradation by UV-B. Total microbial respiration decreased, indicating the decomposers` sensitivity to UV-B. In general, the litter decomposing under UV-B was less colonized by fungal decomposers. Mucor hiemalis and Truncatella truncata were significantly more abundant in the control, indicating sensitivity to UV-B radiation, while Penicillium brevicompactum was equally abundant in the UV-B and control. There is strong indication of a change in decomposer fungal community structure due to UV-B. Just one of the three fungal species common on the control litter was dominant on leaves decomposed under UV-B. (au) (44 refs.)

  18. Elemental composition and optical properties reveal changes in dissolved organic matter along a permafrost thaw chronosequence in a subarctic peatland

    Science.gov (United States)

    Hodgkins, Suzanne B.; Tfaily, Malak M.; Podgorski, David C.; McCalley, Carmody K.; Saleska, Scott R.; Crill, Patrick M.; Rich, Virginia I.; Chanton, Jeffrey P.; Cooper, William T.

    2016-08-01

    The fate of carbon stored in permafrost-zone peatlands represents a significant uncertainty in global climate modeling. Given that the breakdown of dissolved organic matter (DOM) is often a major pathway for decomposition in peatlands, knowledge of DOM reactivity under different permafrost regimes is critical for determining future climate feedbacks. To explore the effects of permafrost thaw and resultant plant succession on DOM reactivity, we used a combination of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), UV/Vis absorbance, and excitation-emission matrix spectroscopy (EEMS) to examine the DOM elemental composition and optical properties of 27 pore water samples gathered from various sites along a permafrost thaw sequence in Stordalen Mire, a thawing subarctic peatland in northern Sweden. The presence of dense Sphagnum moss, a feature that is dominant in the intermediate thaw stages, appeared to be the main driver of variation in DOM elemental composition and optical properties at Stordalen. Specifically, DOM from sites with Sphagnum had greater aromaticity, higher average molecular weights, and greater O/C, consistent with a higher abundance of phenolic compounds that likely inhibit decomposition. These compounds are released by Sphagnum and may accumulate due to inhibition of phenol oxidase activity by the acidic pH at these sites. In contrast, sites without Sphagnum, specifically fully-thawed rich fens, had more saturated, more reduced compounds, which were high in N and S. Optical properties at rich fens indicated the presence of microbially-derived DOM, consistent with the higher decomposition rates previously measured at these sites. These results indicate that Sphagnum acts as an inhibitor of rapid decomposition and CH4 release in thawing subarctic peatlands, consistent with lower rates of CO2 and CH4 production previously observed at these sites. However, this inhibitory effect may disappear if Sphagnum-dominated bogs

  19. Ecological and spatial factors drive intra- and interspecific variation in exposure of subarctic predatory bird nestlings to persistent organic pollutants.

    Science.gov (United States)

    Eulaers, Igor; Jaspers, Veerle L B; Bustnes, Jan O; Covaci, Adrian; Johnsen, Trond V; Halley, Duncan J; Moum, Truls; Ims, Rolf A; Hanssen, Sveinn A; Erikstad, Kjell E; Herzke, Dorte; Sonne, Christian; Ballesteros, Manuel; Pinxten, Rianne; Eens, Marcel

    2013-07-01

    Top predators in northern ecosystems may suffer from exposure to persistent organic pollutants (POPs) as this exposure may synergistically interact with already elevated natural stress in these ecosystems. In the present study, we aimed at identifying biological (sex, body condition), ecological (dietary carbon source, trophic level) and spatial factors (local habitat, regional nest location) that may influence intra- and interspecific variation in exposure of subarctic predatory bird nestlings to polychlorinated biphenyl 153 (CB 153), polybrominated diphenyl ether 47 (BDE 47), dichlorodiphenyldichloroethylene (p,p'-DDE) and hexachlorobenzene (HCB). During three breeding seasons (2008-2010), we sampled body feathers from fully-grown nestlings of three ecologically distinct predatory bird species in subarctic Norway: Northern Goshawk (Accipiter gentilis), White-tailed Eagle (Haliaeetus albicilla) and Golden Eagle (Aquila chrysaetos). The present study analysed, for the first time, body feathers for both POPs and carbon (δ(13)C) and nitrogen (δ(15)N) stable isotopes, thus integrating the dietary carbon source, trophic level and POP exposure for the larger part of the nestling stage. Intraspecific variation in exposure was driven by a combination of ecological and spatial factors, often different for individual compounds. In addition, combinations for individual compounds differed among species. Trophic level and local habitat were the predominant predictors for CB 153, p,p'-DDE and BDE 47, indicating their biomagnification and decreasing levels according to coast>fjord>inland. Variation in exposure may also have been driven by inter-annual variation arisen from primary sources (e.g. p,p'-DDE) and/or possible revolatilisation from secondary sources (e.g. HCB). Interspecific differences in POP exposure were best explained by a combination of trophic level (biomagnification), dietary carbon source (food chain discrimination) and regional nest location (historical POP

  20. Sustainable Agriculture and Climate Change: Producing Potatoes (Solanum tuberosum L. and Bush Beans (Phaseolus vulgaris L. for Improved Food Security and Resilience in a Canadian Subarctic First Nations Community

    Directory of Open Access Journals (Sweden)

    Christine D. Barbeau

    2015-05-01

    Full Text Available Aboriginal people in Canada experience disproportionately high rates of diet-related illnesses, such as obesity and diabetes. Food insecurity has been identified as a contributing factor to these illnesses along with a loss of traditional lifestyle. Current food systems within northern subarctic and arctic regions of Canada rely heavily on imported foods that are expensive (when available, and are environmentally unsustainable. A warming subarctic and arctic climate present challenges, but also offers the opportunity for local agricultural production that can increase food security and promote a more sustainable food system. In this study the feasibility of sustainably growing potatoes (Solanum tuberosum L. utilizing agroforestry practices to enhance food security in remote subarctic communities is explored through a case study in Fort Albany First Nation in northern Ontario, Canada. Potato crops were grown over a two-year period and rotated into plots that had been planted with green bush beans (Phaseolus vulgaris L.. Results showed that potatoes and bush beans could be grown successfully in the subarctic without the use of greenhouses with yields comparable to more conventional high-input agricultural methods. In subarctic Canada, sustainable local food production can help to promote social capital, healthier lifestyles, and food security.

  1. The physiological effects of oil, dispersant and dispersed oil on the bay mussel, Mytilus trossulus, in Arctic/Subarctic conditions.

    Science.gov (United States)

    Counihan, Katrina L

    2018-06-01

    Increasing oil development around Alaska and other Arctic regions elevates the risk for another oil spill. Dispersants are used to mitigate the impact of an oil spill by accelerating natural degradation processes, but the reduced hydrophobicity of dispersed oil may increase its bioavailability to marine organisms. There is limited research on the effect of dispersed oil on cold water species and ecosystems. Therefore, spiked exposure tests were conducted with bay mussels (Mytilus trossulus) in seawater with non-dispersed oil, Corexit 9500 and oil dispersed with different concentrations of Corexit 9500. After three weeks of exposure, acute and chronic physiological impacts were determined. The majority of physiological responses occurred during the first seven days of exposure, with mussels exhibiting significant cytochrome P450 activity, superoxide dismutase activity and heat shock protein levels. Mussels exposed to non-dispersed oil also experienced immune suppression, reduced transcription and higher levels of mortality. After 21 days, mussels in all treatments exhibited evidence of genetic damage, tissue loss and a continued stress response. Bay mussels are useful as indicators of ecosystem health and recovery, and this study was an important step in understanding how non-dispersed oil, dispersant and dispersed oil affect the physiology of this sentinel species in Arctic/subarctic conditions. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Replacement cost valuation of Northern Pintail (Anas acuta) subsistence harvest in Arctic and sub-Arctic North America

    Science.gov (United States)

    Goldstein, Joshua H.; Thogmartin, Wayne E.; Bagstad, Kenneth J.; Dubovsky, James A.; Mattsson, Brady J.; Semmens, Darius J.; López-Hoffman, Laura; Diffendorfer, James E.

    2014-01-01

    Migratory species provide economically beneficial ecosystem services to people throughout their range, yet often, information is lacking about the magnitude and spatial distribution of these benefits at regional scales. We conducted a case study for Northern Pintails (hereafter pintail) in which we quantified regional and sub-regional economic values of subsistence harvest to indigenous communities in Arctic and sub-Arctic North America. As a first step, we used the replacement cost method to quantify the cost of replacing pintail subsistence harvest with the most similar commercially available protein (chicken). For an estimated annual subsistence harvest of ˜15,000 pintail, our mean estimate of the total replacement cost was ˜$63,000 yr−1 ($2010 USD), with sub-regional values ranging from \\$263 yr−1 to \\$21,930 yr−1. Our results provide an order-of-magnitude, conservative estimate of one component of the regional ecosystem-service values of pintails, providing perspective on how spatially explicit values can inform migratory species conservation.

  3. Carbon dioxide, methane and nitrous oxide fluxes from a fire chronosequence in subarctic boreal forests of Canada.

    Science.gov (United States)

    Köster, Egle; Köster, Kajar; Berninger, Frank; Aaltonen, Heidi; Zhou, Xuan; Pumpanen, Jukka

    2017-12-01

    Forest fires are one of the most important natural disturbances in boreal forests, and their occurrence and severity are expected to increase as a result of climate warming. A combination of factors induced by fire leads to a thawing of the near-surface permafrost layer in subarctic boreal forest. Earlier studies reported that an increase in the active layer thickness results in higher carbon dioxide (CO 2 ) and methane (CH 4 ) emissions. We studied changes in CO 2 , CH 4 and nitrous oxide (N 2 O) fluxes in this study, and the significance of several environmental factors that influence the greenhouse gas (GHG) fluxes at three forest sites that last had fires in 2012, 1990 and 1969, and we compared these to a control area that had no fire for at least 100years. The soils in our study acted as sources of CO 2 and N 2 O and sinks for CH 4 . The elapsed time since the last forest fire was the only factor that significantly influenced all studied GHG fluxes. Soil temperature affected the uptake of CH 4 , and the N 2 O fluxes were significantly influenced by nitrogen and carbon content of the soil, and by the active layer depth. Results of our study confirm that the impacts of a forest fire on GHGs last for a rather long period of time in boreal forests, and are influenced by the fire induced changes in the ecosystem. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Optically-derived estimates of phytoplankton size class and taxonomic group biomass in the Eastern Subarctic Pacific Ocean

    Science.gov (United States)

    Zeng, Chen; Rosengard, Sarah Z.; Burt, William; Peña, M. Angelica; Nemcek, Nina; Zeng, Tao; Arrigo, Kevin R.; Tortell, Philippe D.

    2018-06-01

    We evaluate several algorithms for the estimation of phytoplankton size class (PSC) and functional type (PFT) biomass from ship-based optical measurements in the Subarctic Northeast Pacific Ocean. Using underway measurements of particulate absorption and backscatter in surface waters, we derived estimates of PSC/PFT based on chlorophyll-a concentrations (Chl-a), particulate absorption spectra and the wavelength dependence of particulate backscatter. Optically-derived [Chl-a] and phytoplankton absorption measurements were validated against discrete calibration samples, while the derived PSC/PFT estimates were validated using size-fractionated Chl-a measurements and HPLC analysis of diagnostic photosynthetic pigments (DPA). Our results showflo that PSC/PFT algorithms based on [Chl-a] and particulate absorption spectra performed significantly better than the backscatter slope approach. These two more successful algorithms yielded estimates of phytoplankton size classes that agreed well with HPLC-derived DPA estimates (RMSE = 12.9%, and 16.6%, respectively) across a range of hydrographic and productivity regimes. Moreover, the [Chl-a] algorithm produced PSC estimates that agreed well with size-fractionated [Chl-a] measurements, and estimates of the biomass of specific phytoplankton groups that were consistent with values derived from HPLC. Based on these results, we suggest that simple [Chl-a] measurements should be more fully exploited to improve the classification of phytoplankton assemblages in the Northeast Pacific Ocean.

  5. Late Cretaceous climate simulations with different CO2 levels and subarctic gateway configurations: A model-data comparison

    Science.gov (United States)

    Niezgodzki, Igor; Knorr, Gregor; Lohmann, Gerrit; Tyszka, Jarosław; Markwick, Paul J.

    2017-09-01

    We investigate the impact of different CO2 levels and different subarctic gateway configurations on the surface temperatures during the latest Cretaceous using the Earth System Model COSMOS. The simulated temperatures are compared with the surface temperature reconstructions based on a recent compilation of the latest Cretaceous proxies. In our numerical experiments, the CO2 level ranges from 1 to 6 times the preindustrial (PI) CO2 level of 280 ppm. On a global scale, the most reasonable match between modeling and proxy data is obtained for the experiments with 3 to 5 × PI CO2 concentrations. However, the simulated low- (high-) latitude temperatures are too high (low) as compared to the proxy data. The moderate CO2 levels scenarios might be more realistic, if we take into account proxy data and the dead zone effect criterion. Furthermore, we test if the model-data discrepancies can be caused by too simplistic proxy-data interpretations. This is distinctly seen at high latitudes, where most proxies are biased toward summer temperatures. Additional sensitivity experiments with different ocean gateway configurations and constant CO2 level indicate only minor surface temperatures changes (greenhouse worlds is best constrained by temperatures in the midlatitudes.

  6. Characterization of breeding habitats for black and surf scoters in the eastern boreal forest and subarctic regions of Canada

    Science.gov (United States)

    Perry, M.C.; Kidwell, D.M.; Wells, A.M.; Lohnes, E.J.R.; Osenton, P.C.; Altmann, S.H.; Hanson, Alan; Kerekes, Joseph; Paquet, Julie

    2006-01-01

    We analyzed characteristics of wetland habitats used by breeding black scoters (Melanitta nigra) and surf scoters (M. perspicillata) in the eastern boreal forest and subarctic regions of Canada based on satellite telemetry data collected in the spring and summer. During 2002 and 2004, nine black scoters (four males, five females) were tracked to breeding areas in Quebec, Manitoba, and Northwest Territories. In addition, in 2001?04, seven surf scoters (three males, four females) were tracked to breeding areas in Labrador, Quebec, Northwest Territories, and Nunavut. Based on satellite telemetry data, locations of black and surf scoters in breeding areas were not significantly different in regard to latitude and longitude. Presumed breeding areas were manually plotted on topographic maps and percent cover type and water were estimated. Breeding habitat of black scoters was significantly different than that for surf scoters, with black scoters mainly using open (tundra) areas (44%) and surf scoters using mainly forest areas (66%). Surf scoters presumed breeding areas were at significantly higher elevations than areas used by black scoters. Some breeding areas were associated with islands, but the role of islands for breeding areas is equivocal. These results aid in the identification of potentially critical breeding areas and provide a baseline classification of breeding habitats used by these two species.

  7. Tree Species Diversity, Richness, and Similarity in Intact and Degraded Forest in the Tropical Rainforest of the Congo Basin: Case of the Forest of Likouala in the Republic of Congo

    Directory of Open Access Journals (Sweden)

    Suspense Averti Ifo

    2016-01-01

    Full Text Available Trees species diversity, richness, and similarity were studied in fifteen plots of the tropical rainforests in the northeast of the Republic of Congo, based on trees inventories conducted on fifteen 0.25 ha plots installed along different types of forests developed on terra firma, seasonally flooded, and on flooded terra. In all of the plots installed, all trees with diameter at breast height, DBH ≥ 5 cm, were measured. The Shannon diversity index, species richness, equitability, and species dominance were computed to see the variation in tree community among plots but also between primary forest and secondary forest. A total of 1611 trees representing 114 species and 35 families were recorded from a total area of 3.75 ha. Euphorbiaceae was the dominant family in the forest with 12 species, followed by Fabaceae-Mimosoideae (10 species and Phyllanthaceae (6 species and Guttiferae (6 species. The biodiversity did not vary greatly from plot to plot on the whole of the study area (3.75 ha. The low value of Shannon index was obtained in plot 11 (H′=0.75 whereas the highest value was obtained in plot 12 (H′=4.46. The values of this index vary from 0.23 to 0.95 in plots P11 and P15, respectively. Results obtained revealed high biodiversity of trees of the forest of Impfondo-Dongou. The information on tree species structure and function can provide baseline information for conservation of the biodiversity of the tropical forest in this area.

  8. Relative importance of plant uptake and plant associated denitrification for removal of nitrogen from mine drainage in sub-arctic wetlands.

    Science.gov (United States)

    Hallin, Sara; Hellman, Maria; Choudhury, Maidul I; Ecke, Frauke

    2015-11-15

    Reactive nitrogen (N) species released from undetonated ammonium-nitrate based explosives used in mining or other blasting operations are an emerging environmental problem. Wetlands are frequently used to treat N-contaminated water in temperate climate, but knowledge on plant-microbial interactions and treatment potential in sub-arctic wetlands is limited. Here, we compare the relative importance of plant uptake and denitrification among five plant species commonly occurring in sub-arctic wetlands for removal of N in nitrate-rich mine drainage in northern Sweden. Nitrogen uptake and plant associated potential denitrification activity and genetic potential for denitrification based on quantitative PCR of the denitrification genes nirS, nirK, nosZI and nosZII were determined in plants growing both in situ and cultivated in a growth chamber. The growth chamber and in situ studies generated similar results, suggesting high relevance and applicability of results from growth chamber experiments. We identified denitrification as the dominating pathway for N-removal and abundances of denitrification genes were strong indicators of plant associated denitrification activity. The magnitude and direction of the effect differed among the plant species, with the aquatic moss Drepanocladus fluitans showing exceptionally high ratios between denitrification and uptake rates, compared to the other species. However, to acquire realistic estimates of N-removal potential of specific wetlands and their associated plant species, the total plant biomass needs to be considered. The species-specific plant N-uptake and abundance of denitrification genes on the root or plant surfaces were affected by the presence of other plant species, which show that both multi- and inter-trophic interactions are occurring. Future studies on N-removal potential of wetland plant species should consider how to best exploit these interactions in sub-arctic wetlands. Copyright © 2015 Elsevier Ltd. All rights

  9. Importance of Ekman transport and gyre circulation change on seasonal variation of surface dissolved iron in the western subarctic North Pacific

    Science.gov (United States)

    Nakanowatari, Takuya; Nakamura, Tomohiro; Uchimoto, Keisuke; Nishioka, Jun; Mitsudera, Humio; Wakatsuchi, Masaaki

    2017-05-01

    Iron (Fe) is an essential nutrient for marine phytoplankton and it constitutes an important element in the marine carbon cycle in the ocean. This study examined the mechanisms controlling seasonal variation of dissolved Fe (dFe) in the western subarctic North Pacific (WSNP), using an ocean general circulation model coupled with a simple biogeochemical model incorporating a dFe cycle fed by two major sources (atmospheric dust and continental shelf sediment). The model reproduced the seasonal cycle of observed concentrations of dFe and macronutrients at the surface in the Oyashio region with maxima in winter (February-March) and minima in summer (July-September), although the simulated seasonal amplitudes are a half of the observed values. Analysis of the mixed-layer dFe budget indicated that both local vertical entrainment and lateral advection are primary contributors to the wintertime increase in dFe concentration. In early winter, strengthened northwesterly winds excite southward Ekman transport and Ekman upwelling over the western subarctic gyre, transporting dFe-rich water southward. In mid to late winter, the southward western boundary current of the subarctic gyre and the outflow from the Sea of Okhotsk also bring dFe-rich water to the Oyashio region. The contribution of atmospheric dust to the dFe budget is several times smaller than these ocean transport processes in winter. These results suggest that the westerly wind-induced Ekman transport and gyre circulation systematically influence the seasonal cycle of WSNP surface dFe concentration.

  10. Iron availability, nitrate uptake, and exportable new production in the subarctic Pacific. [phytoplankton population growth support and atmospheric CO2 removal

    Science.gov (United States)

    Banse, Karl

    1991-01-01

    This paper presents a critique of experimental data and papers by Martin et al. (1989, 1990), who suggested that the phytoplankton growth is iron-limited and that, small additions of iron to large subarctic ocean areas might be a way of removing significant amounts of atmospheric CO2 by increasing phytoplancton growth. Data are presented to show that, in the summer of 1987, the phytoplankton assemblage as a whole was not iron limited, as measured by the bulk removal of nitrate or by the increase of chlorophyll. It is suggested that grazing normally prevents the phytoplankton from reaching concentrations that reduce the iron (and nitrate) to levels that depress division rates drastically.

  11. Animistic pragmatism and native ways of knowing: adaptive strategies for overcoming the struggle for food in the sub-Arctic

    Directory of Open Access Journals (Sweden)

    Raymond Anthony

    2013-08-01

    Full Text Available Background. Subsistence norms are part of the “ecosophy” or ecological philosophy of Alaska Native Peoples in the sub-Arctic, such as the Inupiat of Seward Peninsula. This kind of animistic pragmatism is a special source of practical wisdom that spans over thousands of years and which has been instrumental in the Iñupiat’s struggle to survive and thrive in harsh and evolving environments. Objective. I hope to show how narrative in relationship to the “ecosophy” of Alaska Native peoples can help to promote a more ecological orientation to address food insecurity in rural communities in Alaska. Alaska Native ecosophy recommends central values and virtues necessary to help address concerns in Alaska’s rural communities. Design. Here, I will tease out the nature of this “ecosophy” in terms of animistic pragmatism and then show why this form of pragmatism can be instrumental for problematizing multi-scalar, intergenerational, uncertain and complex environmental challenges like food security. Results. Native elders have been the embodiment of trans-generational distributed cognition,1 for example, collective memory, norms, information, knowledge, technical skills and experimental adaptive strategies. They are human “supercomputers,” historical epistemologists and moral philosophers of a sort who use narrative, a form of moral testimony, to help their communities face challenges and seize opportunities in the wake of an ever-changing landscape. Conclusions. The “ecosophy” of the Iñupiat of Seward Peninsula offers examples of “focal practices”, which are essential for environmental education. These focal practices instil key virtues, namely humility, gratitude, self-reliance, attentiveness, responsibility and responsiveness, that are necessary for subsistence living.

  12. Warming of subarctic tundra increases emissions of all three important greenhouse gases - carbon dioxide, methane, and nitrous oxide.

    Science.gov (United States)

    Voigt, Carolina; Lamprecht, Richard E; Marushchak, Maija E; Lind, Saara E; Novakovskiy, Alexander; Aurela, Mika; Martikainen, Pertti J; Biasi, Christina

    2017-08-01

    Rapidly rising temperatures in the Arctic might cause a greater release of greenhouse gases (GHGs) to the atmosphere. To study the effect of warming on GHG dynamics, we deployed open-top chambers in a subarctic tundra site in Northeast European Russia. We determined carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O) fluxes as well as the concentration of those gases, inorganic nitrogen (N) and dissolved organic carbon (DOC) along the soil profile. Studied tundra surfaces ranged from mineral to organic soils and from vegetated to unvegetated areas. As a result of air warming, the seasonal GHG budget of the vegetated tundra surfaces shifted from a GHG sink of -300 to -198 g CO 2 -eq m -2 to a source of 105 to 144 g CO 2 -eq m -2 . At bare peat surfaces, we observed increased release of all three GHGs. While the positive warming response was dominated by CO 2 , we provide here the first in situ evidence of increasing N 2 O emissions from tundra soils with warming. Warming promoted N 2 O release not only from bare peat, previously identified as a strong N 2 O source, but also from the abundant, vegetated peat surfaces that do not emit N 2 O under present climate. At these surfaces, elevated temperatures had an adverse effect on plant growth, resulting in lower plant N uptake and, consequently, better N availability for soil microbes. Although the warming was limited to the soil surface and did not alter thaw depth, it increased concentrations of DOC, CO 2, and CH 4 in the soil down to the permafrost table. This can be attributed to downward DOC leaching, fueling microbial activity at depth. Taken together, our results emphasize the tight linkages between plant and soil processes, and different soil layers, which need to be taken into account when predicting the climate change feedback of the Arctic. © 2016 John Wiley & Sons Ltd.

  13. Seasonal changes in nutrients, chlorophyll a and the phytoplankton assemblage of the western subarctic gyre in the Pacific Ocean

    Science.gov (United States)

    Mochizuki, Mamiko; Shiga, Naonobu; Saito, Masaru; Imai, Keiri; Nojiri, Yukihiro

    The standing stock and species composition of phytoplankton (>10 μm) were studied using monthly water samples collected at Stn KNOT (Kyodo North Pacific Ocean Time Series; 44°N, 155°E) in the western subarctic gyre in the Pacific Ocean through June 1998 to June 1999 (except for January-April 1999) and January-February 2000. One-liter water samples were preserved in 1% neutrally buffered formalin. Identification and enumeration of phytoplankton were made with an inverted microscope. Nutrients did not appear to be depleted for phytoplakton growth during any season. The vertical distribution of phytoplankton was primarily restricted by the pycnocline, and the bulk of phytoplankton assemblage existed within the surface mixed layer. In July, however, some senescent cells were observed at 200 m. Phytoplankton abundance clearly showed a spring maximum (i.e. spring bloom) in May. The seasonal change in cell numbers, however, did not coincide closely with the change in chlorophyll a concentration. Centric diatoms, which were composed of Thalassiosira, Chaetoceros, and Coscinodiscus, dominated all year round, and showed temporal succession. Pennate diatoms (mostly Neodenticula seminae and Fragilariopsis) increased only during the spring bloom. Dinoflagellates (mostly Gymnodinium and Prorocentrum) were low in abundance, although they increased in summer when the phytoplankton standing stock was low. Silicoflagellate abundance was extremely low. Comparing the annual species composition of phytoplankton between Stn KNOT and Stn P (50°N, 145°W) in the Alaskan Gyre, there was a remarkable difference between the two sites. The phytoplankton assemblage at Stn P is characterized by a high abundance of Rhizosolenia alata and low abundance of Thalassiosira. In contrast, Thalassiosira dominates at Stn KNOT during most seasons.

  14. Atmospheric iron supply and enhanced vertical carbon flux in the NE subarctic Pacific: Is there a connection?

    Science.gov (United States)

    Boyd, P. W.; Wong, C. S.; Merrill, J.; Whitney, F.; Snow, J.; Harrison, P. J.; Gower, J.

    1998-09-01

    Recent studies have confirmed the relationship between iron supply and phytoplankton growth rates in all three high-nitrate low-chlorophyll (HNLC) oceanic provinces. However, there is little evidence, so far, of the role of iron in altering the efficiency of the biological pump via increased downward export of particulate organic carbon (POC). The NE subarctic Pacific is unique among HNLC regions in that long time series pelagic observations and deep-moored sediment trap records exist which may provide the best opportunity thus far to test aspects of the iron hypothesis. Episodic elevated levels of chlorophyll a (> 2.0 μg L-1) were observed 6 times between 1964 and 1976 at the former site of Ocean Station Papa (OSP). In addition, between 1984 and 1990 on at least three occasions, concurrent pulses of POC and biogenic silica were recorded in deep-moored traps at OSP. Possible explanations for these events, such as lateral advection of more productive waters, iron-mediated blooms, or grazing by salp swarms are discussed and tested using an existing downward POC flux model. Owing to the episodic nature of such events, no available data are sufficiently comprehensive to unequivocally rule out any of these explanations. Nevertheless, from the data available, the occurrence of pelagic or deep water pulses, approximately once every 3 years, are most consistent with iron-mediated diatom blooms, and of the sinking of POC and biogenic silica (from such a bloom) to depth, respectively. A comparison of the timing of these iron-mediated pulses with that of the transport probabilities of atmospheric dust supply from Asia and Alaska provides an opportunity to assess the likelihood of a coupling between the atmosphere and the ocean.

  15. DNA sequencing, anatomy, and calcification patterns support a monophyletic, subarctic, carbonate reef-forming Clathromorphum (Hapalidiaceae, Corallinales, Rhodophyta).

    Science.gov (United States)

    Adey, Walter H; Hernandez-Kantun, Jazmin J; Johnson, Gabriel; Gabrielson, Paul W

    2015-02-01

    For the first time, morpho-anatomical characters that were congruent with DNA sequence data were used to characterize several genera in Hapalidiaceae-the major eco-engineers of Subarctic carbonate ecosystems. DNA sequencing of three genes (SSU, rbcL, ribulose-1, 5-bisphosphate carboxylase/oxygenase large subunit gene and psbA, photosystem II D1 protein gene), along with patterns of cell division, cell elongation, and calcification supported a monophyletic Clathromorphum. Two characters were diagnostic for this genus: (i) cell division, elongation, and primary calcification occurred only in intercalary meristematic cells and in a narrow vertical band (1-2 μm wide) resulting in a "meristem split" and (ii) a secondary calcification of interfilament crystals was also produced. Neopolyporolithon was resurrected for N. reclinatum, the generitype, and Clathromorphum loculosum was transferred to this genus. Like Clathromorphum, cell division, elongation, and calcification occurred only in intercalary meristematic cells, but in a wider vertical band (over 10-20 μm), and a "meristem split" was absent. Callilithophytum gen. nov. was proposed to accommodate Clathromorphum parcum, the obligate epiphyte of the northeast Pacific endemic geniculate coralline, Calliarthron. Diagnostic for this genus were epithallial cells terminating all cell filaments (no dorsi-ventrality was present), and a distinct "foot" was embedded in the host. Leptophytum, based on its generitype, L. laeve, was shown to be a distinct genus more closely related to Clathromorphum than to Phymatolithon. All names of treated species were applied unequivocally by linking partial rbcL sequences from holotype, isotype, or epitype specimens with field-collected material. Variation in rbcL and psbA sequences suggested that multiple species may be passing under each currently recognized species of Clathromorphum and Neopolyporolithon. © 2014 Phycological Society of America.

  16. Feeding ecology of mesopelagic zooplankton of the subtropical and subarctic North Pacific Ocean determined with fatty acid biomarkers

    Science.gov (United States)

    Wilson, S. E.; Steinberg, D. K.; Chu, F.-L. E.; Bishop, J. K. B.

    2010-10-01

    Mesopelagic zooplankton may meet their nutritional and metabolic requirements in a number of ways including consumption of sinking particles, carnivory, and vertical migration. How these feeding modes change with depth or location, however, is poorly known. We analyzed fatty acid (FA) profiles to characterize zooplankton diet and large particle (>51 μm) composition in the mesopelagic zone (base of euphotic zone -1000 m) at two contrasting time-series sites in the subarctic (station K2) and subtropical (station ALOHA) Pacific Ocean. Total FA concentration was 15.5 times higher in zooplankton tissue at K2, largely due to FA storage by seasonal vertical migrators such as Neocalanus and Eucalanus. FA biomarkers specific to herbivory implied a higher plant-derived food source at mesotrophic K2 than at oligotrophic ALOHA. Zooplankton FA biomarkers specific to dinoflagellates and diatoms indicated that diatoms, and to a lesser extent, dinoflagellates were important food sources at K2. At ALOHA, dinoflagellate FAs were more prominent. Bacteria-specific FA biomarkers in zooplankton tissue were used as an indicator of particle feeding, and peaks were recorded at depths where known particle feeders were present at ALOHA (e.g., ostracods at 100-300 m). In contrast, depth profiles of bacterial FA were relatively constant with depth at K2. Diatom, dinoflagellate, and bacterial biomarkers were found in similar proportions in both zooplankton and particles with depth at both locations, providing additional evidence that mesopelagic zooplankton consume sinking particles. Carnivory indices were higher and increased significantly with depth at ALOHA, and exhibited distinct peaks at K2, representing an increase in dependence on other zooplankton for food in deep waters. Our results indicate that feeding ecology changes with depth as well as by location. These changes in zooplankton feeding ecology from the surface through the mesopelagic zone, and between contrasting environments

  17. Animistic pragmatism and native ways of knowing: adaptive strategies for overcoming the struggle for food in the sub-Arctic

    Science.gov (United States)

    Anthony, Raymond

    2013-01-01

    Background Subsistence norms are part of the “ecosophy” or ecological philosophy of Alaska Native Peoples in the sub-Arctic, such as the Inupiat of Seward Peninsula. This kind of animistic pragmatism is a special source of practical wisdom that spans over thousands of years and which has been instrumental in the Iñupiat's struggle to survive and thrive in harsh and evolving environments. Objective I hope to show how narrative in relationship to the “ecosophy” of Alaska Native peoples can help to promote a more ecological orientation to address food insecurity in rural communities in Alaska. Alaska Native ecosophy recommends central values and virtues necessary to help address concerns in Alaska's rural communities. Design Here, I will tease out the nature of this “ecosophy” in terms of animistic pragmatism and then show why this form of pragmatism can be instrumental for problematizing multi-scalar, intergenerational, uncertain and complex environmental challenges like food security. Results Native elders have been the embodiment of trans-generational distributed cognition,1 for example, collective memory, norms, information, knowledge, technical skills and experimental adaptive strategies. They are human “supercomputers,” historical epistemologists and moral philosophers of a sort who use narrative, a form of moral testimony, to help their communities face challenges and seize opportunities in the wake of an ever-changing landscape. Conclusions The “ecosophy” of the Iñupiat of Seward Peninsula offers examples of “focal practices”, which are essential for environmental education. These focal practices instil key virtues, namely humility, gratitude, self-reliance, attentiveness, responsibility and responsiveness, that are necessary for subsistence living. PMID:23986900

  18. Year-Round Carbon Fluxes in a Subarctic Landscape Show the Importance of Lake Emissions According to Season

    Science.gov (United States)

    Jammet, M.; Crill, P. M.; Friborg, T.

    2014-12-01

    Lakes are increasingly recognized as important components of the global terrestrial carbon budget. Northern lakes are especially of interest due to a high density of open-water ecosystems in Northern latitudes and a potential increase in lake areal extent where permafrost is thawing. A better understanding of lake-atmosphere interactions requires long-term and direct measurement of surface fluxes. This is rarely achieved in Northern landscapes where seasonally ice-covered lakes are mostly studied during the open water season, and measurement methods do not always allow an integration of all gas transport pathways to the atmosphere. We present here ecosystem-scale data from Stordalen (68°20'N, 19°03'E), a thawing permafrost peatland in subarctic Sweden, where an eddy covariance system is used in an innovative way to quantify the importance of methane (CH4) emissions from a shallow lake. After more than a year of surface flux monitoring, it is found that spring is a crucial season for lake-atmosphere CH4 exchange. Despite its shallow depth, more than half of annual CH4 emissions from the lake were recorded at ice-out, suggesting significant winter CH4 production in lake sediments. Lake water dynamics seemed to drive the observed spring release rates. In contrast, summer methane emissions in Stordalen were dominated by the minerotrophic fens. This underlines the importance of considering the full annual budget when assessing the carbon source strength of seasonally ice-covered lakes. Carbon dioxide fluxes were also monitored and will be briefly discussed, as well as the significance of northern lakes spring burst for global atmospheric CH4 budget.

  19. Analyzing tree cores to detect petroleum hydrocarbon-contaminated groundwater at a former landfill site in the community of Happy Valley-Goose Bay, eastern Canadian subarctic.

    Science.gov (United States)

    Fonkwe, Merline L D; Trapp, Stefan

    2016-08-01

    This research examines the feasibility of analyzing tree cores to detect benzene, toluene, ethylbenzene, and m, p, o-xylene (BTEX) compounds and methyl tertiary-butyl ether (MTBE) in groundwater in eastern Canada subarctic environments, using a former landfill site in the remote community of Happy Valley-Goose Bay, Labrador. Petroleum hydrocarbon contamination at the landfill site is the result of environmentally unsound pre-1990s disposal of households and industrial solid wastes. Tree cores were taken from trembling aspen, black spruce, and white birch and analyzed by headspace-gas chromatography-mass spectrometry. BTEX compounds were detected in tree cores, corroborating known groundwater contamination. A zone of anomalously high concentrations of total BTEX constituents was identified and recommended for monitoring by groundwater wells. Tree cores collected outside the landfill site at a local control area suggest the migration of contaminants off-site. Tree species exhibit different concentrations of BTEX constituents, indicating selective uptake and accumulation. Toluene in wood exhibited the highest concentrations, which may also be due to endogenous production. Meanwhile, MTBE was not found in the tree cores and is considered to be absent in the groundwater. The results demonstrate that tree-core analysis can be useful for detecting anomalous concentrations of petroleum hydrocarbons, such as BTEX compounds, in subarctic sites with shallow unconfined aquifers and permeable soils. This method can therefore aid in the proper management of contamination during landfill operations and after site closures.

  20. Anatomical structure overrides temperature controls on magnesium uptake – calcification in the Arctic/subarctic coralline algae Leptophytum laeve and Kvaleya epilaeve (Rhodophyta; Corallinales

    Directory of Open Access Journals (Sweden)

    M. C. Nash

    2018-02-01

    Full Text Available Calcified coralline red algae are ecologically key organisms in photic benthic environments. In recent decades they have become important climate proxies, especially in the Arctic and subarctic. It has been widely accepted that magnesium content in coralline tissues is directly a function of ambient temperature, and this is a primary basis for their value as a climate archive. In this paper we show for two genera of Arctic/subarctic corallines, Leptophytum laeve and Kvaleya epilaeve, that previously unrecognised complex tissue and cell wall anatomy bears a variety of basal signatures for Mg content, with the accepted temperature relationship being secondary. The interfilament carbonate has lower Mg than adjacent cell walls and the hypothallial cell walls have the highest Mg content. The internal structure of the hypothallial cell walls can differ substantially from the perithallial radial cell wall structure. Using high-magnification scanning electron microscopy and etching we expose the nanometre-scale structures within the cell walls and interfilament. Fibrils concentrate at the internal and external edges of the cell walls. Fibrils  ∼  10 nm thick appear to thread through the radial Mg-calcite grains and form concentric bands within the cell wall. This banding may control Mg distribution within the cell. Similar fibril banding is present in the hypothallial cell walls but not the interfilament. Climate archiving with corallines can achieve greater precision with recognition of these parameters.

  1. Anatomical structure overrides temperature controls on magnesium uptake - calcification in the Arctic/subarctic coralline algae Leptophytum laeve and Kvaleya epilaeve (Rhodophyta; Corallinales)

    Science.gov (United States)

    Nash, Merinda C.; Adey, Walter

    2018-02-01

    Calcified coralline red algae are ecologically key organisms in photic benthic environments. In recent decades they have become important climate proxies, especially in the Arctic and subarctic. It has been widely accepted that magnesium content in coralline tissues is directly a function of ambient temperature, and this is a primary basis for their value as a climate archive. In this paper we show for two genera of Arctic/subarctic corallines, Leptophytum laeve and Kvaleya epilaeve, that previously unrecognised complex tissue and cell wall anatomy bears a variety of basal signatures for Mg content, with the accepted temperature relationship being secondary. The interfilament carbonate has lower Mg than adjacent cell walls and the hypothallial cell walls have the highest Mg content. The internal structure of the hypothallial cell walls can differ substantially from the perithallial radial cell wall structure. Using high-magnification scanning electron microscopy and etching we expose the nanometre-scale structures within the cell walls and interfilament. Fibrils concentrate at the internal and external edges of the cell walls. Fibrils ˜ 10 nm thick appear to thread through the radial Mg-calcite grains and form concentric bands within the cell wall. This banding may control Mg distribution within the cell. Similar fibril banding is present in the hypothallial cell walls but not the interfilament. Climate archiving with corallines can achieve greater precision with recognition of these parameters.

  2. Seasonal climate manipulations have only minor effects on litter decomposition rates and N dynamics but strong effects on litter P dynamics of sub-arctic bog species.

    Science.gov (United States)

    Aerts, R; Callaghan, T V; Dorrepaal, E; van Logtestijn, R S P; Cornelissen, J H C

    2012-11-01

    Litter decomposition and nutrient mineralization in high-latitude peatlands are constrained by low temperatures. So far, little is known about the effects of seasonal components of climate change (higher spring and summer temperatures, more snow which leads to higher winter soil temperatures) on these processes. In a 4-year field experiment, we manipulated these seasonal components in a sub-arctic bog and studied the effects on the decomposition and N and P dynamics of leaf litter of Calamagrostis lapponica, Betula nana, and Rubus chamaemorus, incubated both in a common ambient environment and in the treatment plots. Mass loss in the controls increased in the order Calamagrostis Litter chemistry showed within each incubation environment only a few and species-specific responses. Compared to the interspecific differences, they resulted in only moderate climate treatment effects on mass loss and these differed among seasons and species. Neither N nor P mineralization in the litter were affected by the incubation environment. Remarkably, for all species, no net N mineralization had occurred in any of the treatments during 4 years. Species differed in P-release patterns, and summer warming strongly stimulated P release for all species. Thus, moderate changes in summer temperatures and/or winter snow addition have limited effects on litter decomposition rates and N dynamics, but summer warming does stimulate litter P release. As a result, N-limitation of plant growth in this sub-arctic bog may be sustained or even further promoted.

  3. Monitoring of the invasive diatom Didymosphenia geminata in the subarctic and in alpine areas of southern Europe

    Science.gov (United States)

    Finger, David C.; Jónsson, Ingi R.; Cypaité, Vaiva; Ognjanova, Nadja; Ólafsson, Jón S.; Trichkova, Teodora

    2016-04-01

    In recent decades invasive species have been spreading across Europe. Although the perceptions of invasive species are divergent among researchers there is a general consent that invasive species endanger the diversity of native biota and hence should be monitored to initiate appropriate counter measures in drastic cases. Anthropogenic activities and climate change are the main cause for the enhanced spreading of non-native species to new environments. In this presentation we will present preliminary results from two aquatic case studies, one located in subarctic Iceland (River Elliðaár) and one in the high mountains of Bulgaria (the Seven Rila lakes), focusing on the freshwater diatom Didymosphenia geminata (Didymo). The diatom is a single cell algae which's natural habitat is cold fresh water environments with low nutrient content, i.e. mountainous areas in Europe, Asia and North America. In the last decades Didymo has been increasingly observed in new areas, e.g. Iceland, North America and New Zealand. Within the ESENIAS-TOOLS project two field excursions will identify the existence of Didymo in the two study sites and compare current abundance to previous observations. The preliminary results in the Rila Mountains, including both fossil and recent records, confirm that the occurrence of Didymo is restricted to Lake Bliznaka, the largest of the seven lakes located at lower altitude. In River Elliðaár preliminary results indicate a high abundance of Didymo along all sampling locations, confirming the invasive proliferation described in previous studies. The upscaling of the preliminary results from Elliðaár and Rila Mountains can help us to formulate general conclusions about the spreading of this invasive species. Furthermore, this bilateral cooperation can be further extended to other countries and hence contribute to a better management of invasive alien species in Europe. Acknowledgement: This study is part of ESENIAS - The East and South European

  4. Primary, new and export production in the NW Pacific subarctic gyre during the vertigo K2 experiments

    Science.gov (United States)

    Elskens, M.; Brion, N.; Buesseler, K.; Van Mooy, B. A. S.; Boyd, P.; Dehairs, F.; Savoye, N.; Baeyens, W.

    2008-07-01

    This paper presents results on tracer experiments using 13C and 15N to estimate uptake rates of dissolved inorganic carbon (DIC) and nitrogen (DIN). Experiments were carried out at station K2 (47°N, 161°E) in the NW Pacific subarctic gyre during July-August 2005. Our goal was to investigate relationships between new and export production. New production was inferred from the tracer experiments using the f ratio concept (0-50 m); while export production was assessed with neutrally buoyant sediment traps (NBSTs) and the e ratio concept (at 150 m). During trap deployments, K2 was characterized both by changes in primary production (523-404 mg C m -2 d -1), new production (119-67 mg C m -2 d -1), export production (68-24 mg C m -2 d -1) and phytoplankton composition (high to low proportion of diatoms). The data indicate that 17-23% of primary production is exportable to deeper layers ( f ratio) but only 6-13% collected as a sinking particle flux at 150 m ( e ratio). Accordingly, >80% of the carbon fixed by phytoplankton would be mineralized in the upper 50 m (1- f), while <11% would be within 50-150 m ( f- e). DIN uptake flux amounted to 0.5 mM m -2 h -1, which was equivalent to about 95% particulate nitrogen (PN) remineralized and/or grazed within the upper 150 m. Most of the shallow PN remineralization occurred just above the depth of the deep chlorophyll maximum (DCM), where a net ammonium production was measured. Below the DCM, while nitrate uptake rates became negligible because of light limitation, ammonium uptake did continue to be significant. The uptake of ammonium by heterotrophic bacteria was estimated to be 14-17% of the DIN assimilation. Less clear are the consequences of this uptake on the phytoplankton community and biogeochemical processes, e.g. new production. It was suggested that competition for ammonium could select for small cells and may force large diatoms to use nitrate. This implies that under Fe stress as observed here, ammonium uptake is

  5. Effects of Accelerated Deglaciation on Chemical Characteristics of Sub-arctic Lakes and Rivers in South and West Iceland

    Science.gov (United States)

    Ritter, M.; Strock, K.; Edwards, B. R.

    2017-12-01

    Glaciers and their associated paraglacial landscapes have changed rapidly over the past century, and may see increased rates of melt as temperatures increase in high latitude environments. As glaciers recede, glacial meltwater subsidies increase to inland freshwater systems, influencing their structure and function. Evidence suggests melting ice influences the chemical characteristics of systems by providing nutrient subsidies, while inputs of glacial flour influence their physical structure by affecting temperature, reducing water clarity and increasing turbidity. Together, changes in physical and chemical structure of these systems have subsequent effects on biota, with the potential to lower taxonomic richness. This study characterized the chemistry of rivers and lakes fed by glacial meltwater in sub-arctic environments of Iceland, where there is limited limnological data. The survey characterized nutrient chemistry, dissolved organic carbon, and ion chemistry. We surveyed glacial meltwater from six glaciers in south and west Iceland, using the drainage basin of Gigjökull glacier along the southern coast as a detailed study area to examine the interactions between groundwater and surface runoff. The southern systems, within the Eastern Volcanic Zone, have minimal soil development and active volcanoes produce ash input to lakes. Lakes in the Western Volcanic Zone were more diverse, located in older bedrock with more extensively weathered soil. Key differences were observed between aquatic environments subsidized with glacial meltwater and those without. This included physical effects, such as lower temperatures and chemical effects such as lower conductivity and higher pH in glacially fed systems. In the drainage basin of Gigjökull glacier, lakes formed after the former lagoon was emptied and then partly refilled with debris from jokulhlaups during the 2010 Eyjafjallajökull eruption. These newly formed lakes resembled non-glacial melt systems despite receiving

  6. Effects of enhanced ultraviolet-B radiation on terrestrial subarctic ecosystems and implications for interactions with increased atmospheric CO2

    International Nuclear Information System (INIS)

    Gehrke, C.; Johanson, U.; Bjoern, L.O.; Gwynn-Jones, D.; Callaghan, T.V.; Lee, J.A.

    1996-01-01

    Two predominating types of ecosystems in the Subarctic were exposed to simulated environmental perturbations. A heathland ecosystem was exposed to enhanced UV-B (corresponding to 15% ozone depletion) combined with either increased CO 2 (600 ppm) or additional watering. An ombrotrophic peatland ecosystem was exposed to only enhanced UV-B. Responses both at a plant species level, including different growth forms and life strategies, and at a trophic level (decomposition of organic matter) were studied. There were differences both in the magnitude and direction of plant responses to enhanced UV-B. The four dwarf shrub species in the heathland developed shorter stems, though not at a significant level in the two deciduous species. The leaves of the evergreen, thick-leaved V. vitus-idaea grew thicker under enhanced UV-B, while leaves of the two deciduous species V. myrtillus and V. uliginosum grew thinner. The heathland moss H. splendens showed reduced growth after two and three years under enhanced UV-B but when water was applied simultaneously growth was stimulated by enhanced UV-B. The peat moss S. fuscum had 20% less height increment during the first growing season under enhanced UV-B. Mosses tended to respond quicker to a change in UV-B regime than long-lived dwarf shrubs did. They responded in growth and phenological development already after a few weeks of treatment. Enhanced UV-B in the heathland affected decomposition of organic matter. It had direct negative effects on decomposer community function and structure and indirect negative effects on turnover of V. uliginosum leaf litter by changing the tissue quality of the litter. This was confirmed by studies in the field with another deciduous dwarf shrub (V. myrtillus). Increased growth due to enhanced CO 2 was recorded in V. myrtillus during the first growing season. No change in growth was apparent in any of the dwarf shrubs on a longer-term perspective but the number of flowers and berries were increased in

  7. Role of EPS, Dispersant and Nutrients on the Microbial Response and MOS Formation in the Subarctic Northeast Atlantic

    Directory of Open Access Journals (Sweden)

    Tony Gutierrez

    2017-04-01

    Full Text Available In this study we report the formation of marine oil snow (MOS, its associated microbial community, the factors influencing its formation, and the microbial response to crude oil in surface waters of the Faroe-Shetland Channel (FSC. The FSC is a subarctic region that is hydrodynamically complex located in the northeast Atlantic where oil extraction is currently occurring and where exploration is likely to expand into its deeper waters (>500 m. A major oil spill in this region may mirror the aftermath that ensued following the Deepwater Horizon (DWH blowout in the Gulf of Mexico, where the massive influx of Macondo crude oil triggered the formation of copious quantities of rapidly sinking MOS and successional blooms of opportunistic oil-degrading bacteria. In laboratory experiments, we simulated environmental conditions in sea surface waters of the FSC using water collected from this site during the winter of 2015. We demonstrated that the presence of dispersant triggers the formation of MOS, and that nutrient amendments magnify this. Illumina MiSeq sequencing revealed the enrichment on MOS of associated oil-degrading (Cycloclasticus, Thalassolituus, Marinobacter and EPS-producing (Halomonas, Pseudoalteromonas, Alteromonas bacteria, and included major representation by Psychrobacter and Cobetia with putative oil-degrading/EPS-producing qualities. The formation of marine snow, in the absence of crude oil and dispersant, in seawater amended with nutrients alone indicated that the de novo synthesis of bacterial EPS is a key factor in MOS formation, and the glycoprotein composition of the MOS aggregates confirmed that its amorphous biopolymeric matrix was of microbial (likely bacterial origin. The presence of dispersants and crude oil with/without nutrients resulted in distinct microbial responses marked by intermittent, and in some cases short-lived, blooms of opportunistic heterotrophs, principally obligate hydrocarbonoclastic (Alcanivorax

  8. A Greener Arctic: Vascular Plant Litter Input in Subarctic Peat Bogs Changes Soil Invertebrate Diets and Decomposition Patterns

    Science.gov (United States)

    Krab, E. J.; Berg, M. P.; Aerts, R.; van Logtestijn, R. S. P.; Cornelissen, H. H. C.

    2014-12-01

    Climate-change-induced trends towards shrub dominance in subarctic, moss-dominated peatlands will most likely have large effects on soil carbon (C) dynamics through an input of more easily decomposable litter. The mechanisms by which this increase in vascular litter input interacts with the abundance and diet-choice of the decomposer community to alter C-processing have, however, not yet been unraveled. We used a novel 13C tracer approach to link invertebrate species composition (Collembola), abundance and species-specific feeding behavior to C-processing of vascular and peat moss litters. We incubated different litter mixtures, 100% Sphagnum moss litter, 100% Betula leaf litter, and a 50/50 mixture of both, in mesocosms for 406 days. We revealed the transfer of C from the litters to the soil invertebrate species by 13C labeling of each of the litter types and assessed 13C signatures of the invertebrates Collembola species composition differed significantly between Sphagnum and Betula litter. Within the 'single type litter' mesocosms, Collembola species showed different 13C signatures, implying species-specific differences in diet choice. Surprisingly, the species composition and Collembola abundance changed relatively little as a consequence of Betula input to a Sphagnum based system. Their diet choice, however, changed drastically; species-specific differences in diet choice disappeared and approximately 67% of the food ingested by all Collembola originated from Betula litter. Furthermore, litter decomposition patterns corresponded to these findings; mass loss of Betula increased from 16.1% to 26.2% when decomposing in combination with Sphagnum, while Sphagnum decomposed even slower in combination with Betula litter (1.9%) than alone (4.7%). This study is the first to empirically show that collective diet shifts of the peatland decomposer community from mosses towards vascular plant litter may drive altered decomposition patterns. In addition, we showed that

  9. Analyzing tree cores to detect petroleum hydrocarbon-contaminated groundwater at a former landfill site in the community of Happy Valley-Goose Bay, eastern Canadian subarctic

    DEFF Research Database (Denmark)

    Fonkwe, Merline L D; Trapp, Stefan

    2016-01-01

    -gas chromatography-mass spectrometry. BTEX compounds were detected in tree cores, corroborating known groundwater contamination. A zone of anomalously high concentrations of total BTEX constituents was identified and recommended for monitoring by groundwater wells. Tree cores collected outside the landfill site......This research examines the feasibility of analyzing tree cores to detect benzene, toluene, ethylbenzene, and m, p, o-xylene (BTEX) compounds and methyl tertiary-butyl ether (MTBE) in groundwater in eastern Canada subarctic environments, using a former landfill site in the remote community of Happy...... Valley-Goose Bay, Labrador. Petroleum hydrocarbon contamination at the landfill site is the result of environmentally unsound pre-1990s disposal of households and industrial solid wastes. Tree cores were taken from trembling aspen, black spruce, and white birch and analyzed by headspace...

  10. Effect of the temperature and the exclusion of UVB radiation on the phenolics and iridoids in Menyanthes trifoliata L. leaves in the subarctic

    Energy Technology Data Exchange (ETDEWEB)

    Martz, Francoise [Arctic Centre, University of Lapland, POB 122, FI-96101 Rovaniemi (Finland); Finnish Forest Research Institute, Rovaniemi Research Unit, POB 16, FI-96301 Rovaniemi (Finland); Turunen, Minna, E-mail: minna.turunen@ulapland.f [Arctic Centre, University of Lapland, POB 122, FI-96101 Rovaniemi (Finland); Julkunen-Tiitto, Riitta [Natural Product Research Laboratories, Faculty of Biosciences, University of Joensuu, POB 111, FI-80101 Joensuu (Finland); Lakkala, Kaisa [Arctic Research Centre, Finnish Meteorological Institute (FMI-ARC), Taehtelaentie, 62, FI-99600 Sodankylae (Finland); Sutinen, Marja-Liisa [Finnish Forest Research Institute, Rovaniemi Research Unit, POB 16, FI-96301 Rovaniemi (Finland); Department of Biology, University of Oulu, POB 3000, FI-90014 University of Oulu (Finland)

    2009-12-15

    The long-term effects of UVB exclusion and temperature on the methanol extractable (ME) phenolics (flavonoids, phenolic acids) and iridoids of Menyanthes trifoliata L. (Mt) leaves were studied in northern Finland (68 deg. N) using wooden frames covered with filters for UVB exclusion (polyester filter), control (cellulose acetate filter) and ambient (no filter) conditions. Analysis of ambient plots showed no effect of the daily mean temperature (2sigma = 1.58 deg. C) on the leaf ME compound content and composition, but minimum temperatures decreased the flavonol content. UVB exclusion did not affect the total ME compound content but significantly decreased the proportion of flavonols concomitantly with an increase in iridoids. Due to its high iridoid content, Mt appears as an interesting model plant for studying the iridoid biosynthesis and its regulation under stress conditions. - This study shows that exclusion of UVB radiation modified the content of flavonols and iridoids but not chlorogenic acids in leaves of Menyanthes trifoliata in the subarctic.

  11. The fate of 13C15N labelled glycine in permafrost and surface soil at simulated thaw in mesocosms from high arctic and subarctic ecosystems

    DEFF Research Database (Denmark)

    Ravn, Nynne Marie Rand; Elberling, Bo; Michelsen, Anders

    2017-01-01

    Background and aim: Nutrient distribution and carbon fluxes upon spring thaw are compared in mesocosms from high arctic and subarctic ecosystems dominated by Cassiope tetragona or Salix hastata/Salix arctica, in order to evaluate the possibility of plant and microbial utilization of an organic...... compound in thawing permafrost and surface soil. Methods: Double labeled glycine (13C15N) was added to soil columns with vegetation and to permafrost. During thaw conditions ecosystem respiration 13C was measured and 13C and 15N distribution in the ecosystem pools was quantified one day and one month after...... glycine addition. Results: Near-surface soil microbes were more efficient in the uptake of intact glycine immediately upon thaw than plants. After one month plants had gained more 15N whereas microbes seemed to lose 15N originating from glycine. We observed a time lag in glycine degradation upon...

  12. Long-term addition of fertilizer, labile carbon, and fungicide alters the biomass of plant functional groups in a subarctic-alpine community

    DEFF Research Database (Denmark)

    Haugwitz-Hardenberg-Reventlow, M S; Michelsen, A.

    2011-01-01

    experiment on a subarctic-alpine fellfield dominated by woody evergreen shrubs, bryophytes, and lichens. To manipulate nutrient availability additions of NPK fertilizer, labile C, and fungicide (benomyl) were done in a fully factorial design, replicated in six blocks. The treatments were run for 10 years...... vascular plant groups. Also, limitation of soil nutrient availability caused by labile C addition decreased the relative proportion of green shoots in evergreen shrubs, although these were expected to cope better with the nutrient limitation than the opportunistic graminoids, which, by contrast, were...... unaffected. Reduced fungal biomass due to benomyl addition was accompanied by increased evergreen shrub and clubmoss biomass. Taken together, the effects of treatments were most pronounced 16 years after initiation of the experiment, but despite changes in biomass the overall plant community composition...

  13. Dynamics of particulate and dissolved organic and inorganic phosphorus during the peak and declining phase of an iron-induced phytoplankton bloom in the eastern subarctic Pacific

    Science.gov (United States)

    Yoshimura, Takeshi; Nishioka, Jun; Ogawa, Hiroshi; Tsuda, Atsushi

    2018-01-01

    Phosphorus (P) is an essential element for all organisms and thus the P cycle plays a key role in determining the dynamics of lower trophic levels in marine ecosystems. P in seawater occurs conceptually in particulate and dissolved organic and inorganic (POP, PIP, DOP, and DIP, respectively) pools and clarification of the dynamics in these P pools is the basis to assess the biogeochemical cycle of P. Despite its importance, behaviors of each P pool with phytoplankton dynamics have not been fully examined. We measured the four operationally defined P pools (POPop, PIPop, DOPop, and SRP) during an iron-induced phytoplankton bloom (as part of the subarctic ecosystem response to iron enrichment study (SERIES)) in the eastern subarctic Pacific in summer 2002. During our observations of the iron-enriched patch from day 15 to day 26 after the iron infusion, chlorophyll-a concentration in the surface layer decreased from 6.3 to 1.2 μg L- 1, indicating the peak through decline phase of the phytoplankton bloom. At the bloom peak, P was partitioned into POPop, PIPop, and DOPop in proportions of 60, 27, and 13%, respectively. While chlorophyll-a and POPop showed similar temporal variations during the declining phase, PIPop showed a different peak timing with a 2 day delay compared to POPop, resulting in a rapid change in the relative proportion of PIPop to total particulate P (TPP = POPop + PIPop) at the peak (25%) and during the declining phase of the bloom (50%). A part of POPop was replaced by PIPop just after slowing down of phytoplankton growth. This process may have a significant role in the subsequent regeneration of P. We conclude that measurement of TPP alone is insufficient to show the interaction between P and phytoplankton dynamics and fractionation of TPP into POPop and PIPop provides useful insights to clarify the biogeochemical cycle of P.

  14. IDENTIFICATION AND ASSESSMENT OF DOMOIC ACID PRODUCTION IN OCEANIC PSEUDO-NITZSCHIA (BACILLARIOPHYCEAE) FROM IRON-LIMITED WATERS IN THE NORTHEAST SUBARCTIC PACIFIC(1).

    Science.gov (United States)

    Marchetti, Adrian; Lundholm, Nina; Kotaki, Yuichi; Hubbard, Katherine; Harrison, Paul J; Virginia Armbrust, E

    2008-06-01

    We identified and investigated the potential toxicity of oceanic Pseudo-nitzschia species from Ocean Station Papa (OSP), located in a high-nitrate, low-chlorophyll (HNLC) region of the northeast (NE) subarctic Pacific Ocean. Despite their relatively low abundances in the indigenous phytoplankton assemblage, Pseudo-nitzschia species richness is high. The morphometric characteristics of five oceanic Pseudo-nitzschia isolates from at least four species are described using SEM and TEM. The species identified are Pseudo-nitzschia dolorosa Lundholm et Moestrup, P. granii Hasle, P. heimii Manguin, and P. cf. turgidula (Hust.) Hasle. Additional support for the taxonomic classifications based on frustule morphology is provided through the sequencing of the internal transcribed spacer 1 (ITS1) rDNA. Pseudo-nitzschia species identification was also assessed by the construction of ITS1 clone libraries and using automated ribosomal intergenic spacer analysis (ARISA) for environmental samples collected during the Subarctic Ecosystem Response to Iron Enrichment Study (SERIES), conducted in close proximity to OSP in July of 2002. Based on ITS1 sequences, the presence of P. granii, P. heimii, P. cf. turgidula, and at least five other putative, unidentified Pseudo-nitzschia ITS1 variants was confirmed within iron-enriched phytoplankton assemblages at OSP. None of the oceanic isolates produced detectable levels of particulate domoic acid (DA) when in prolonged stationary phase due to silicic acid starvation. The lack of detectable concentrations of DA suggests that either these strains produce very little or no toxin, or that the physiological conditions required to promote particulate DA production were not met and thus differ from their coastal, toxigenic congeners. © 2008 Phycological Society of America.

  15. Uncertainty assessment of a polygon database of soil organic carbon for greenhouse gas reporting in Canada’s Arctic and sub-arctic

    Directory of Open Access Journals (Sweden)

    M.F. Hossain

    2014-08-01

    Full Text Available Canada’s Arctic and sub-arctic consist 46% of Canada’s landmass and contain 45% of the total soil organic carbon (SOC. Pronounced climate warming and increasing human disturbances could induce the release of this SOC to the atmosphere as greenhouse gases. Canada is committed to estimating and reporting the greenhouse gases emissions and removals induced by land use change in the Arctic and sub-arctic. To assess the uncertainty of the estimate, we compiled a site-measured SOC database for Canada’s north, and used it to compare with a polygon database, that will be used for estimating SOC for the UNFCCC reporting. In 10 polygons where 3 or more measured sites were well located in each polygon, the site-averaged SOC content agreed with the polygon data within ±33% for the top 30 cm and within ±50% for the top 1 m soil. If we directly compared the SOC of the 382 measured sites with the polygon mean SOC, there was poor agreement: The relative error was less than 50% at 40% of the sites, and less than 100% at 68% of the sites. The relative errors were more than 400% at 10% of the sites. These comparisons indicate that the polygon database is too coarse to represent the SOC conditions for individual sites. The difference is close to the uncertainty range for reporting. The spatial database could be improved by relating site and polygon SOC data with more easily observable surface features that can be identified and derived from remote sensing imagery.

  16. Numerical responses of saproxylic beetles to rapid increases in dead wood availability following geometrid moth outbreaks in sub-arctic mountain birch forest.

    Science.gov (United States)

    Vindstad, Ole Petter Laksforsmo; Schultze, Sabrina; Jepsen, Jane Uhd; Biuw, Martin; Kapari, Lauri; Sverdrup-Thygeson, Anne; Ims, Rolf Anker

    2014-01-01

    Saproxylic insects play an important part in decomposing dead wood in healthy forest ecosystems, but little is known about their role in the aftermath of large-scale forest mortality caused by pest insect outbreaks. We used window traps to study short-term changes in the abundance and community structure of saproxylic beetles following extensive mortality of mountain birch in sub-arctic northern Norway caused by an outbreak of geometrid moths. Three to five years after the outbreak, the proportion of obligate saproxylic individuals in the beetle community was roughly 10% higher in forest damaged by the outbreak than in undamaged forest. This was mainly due to two early-successional saproxylic beetle species. Facultative saproxylic beetles showed no consistent differences between damaged and undamaged forest. These findings would suggest a weak numerical response of the saproxylic beetle community to the dead wood left by the outbreak. We suggest that species-specific preferences for certain wood decay stages may limit the number of saproxylic species that respond numerically to an outbreak at a particular time, and that increases in responding species may be constrained by limitations to the amount of dead wood that can be exploited within a given timeframe (i.e. satiation effects). Low diversity of beetle species or slow development of larvae in our cold sub-arctic study region may also limit numerical responses. Our study suggests that saproxylic beetles, owing to weak numerical responses, may so far have played a minor role in decomposing the vast quantities of dead wood left by the moth outbreak.

  17. Numerical responses of saproxylic beetles to rapid increases in dead wood availability following geometrid moth outbreaks in sub-arctic mountain birch forest.

    Directory of Open Access Journals (Sweden)

    Ole Petter Laksforsmo Vindstad

    Full Text Available Saproxylic insects play an important part in decomposing dead wood in healthy forest ecosystems, but little is known about their role in the aftermath of large-scale forest mortality caused by pest insect outbreaks. We used window traps to study short-term changes in the abundance and community structure of saproxylic beetles following extensive mortality of mountain birch in sub-arctic northern Norway caused by an outbreak of geometrid moths. Three to five years after the outbreak, the proportion of obligate saproxylic individuals in the beetle community was roughly 10% higher in forest damaged by the outbreak than in undamaged forest. This was mainly due to two early-successional saproxylic beetle species. Facultative saproxylic beetles showed no consistent differences between damaged and undamaged forest. These findings would suggest a weak numerical response of the saproxylic beetle community to the dead wood left by the outbreak. We suggest that species-specific preferences for certain wood decay stages may limit the number of saproxylic species that respond numerically to an outbreak at a particular time, and that increases in responding species may be constrained by limitations to the amount of dead wood that can be exploited within a given timeframe (i.e. satiation effects. Low diversity of beetle species or slow development of larvae in our cold sub-arctic study region may also limit numerical responses. Our study suggests that saproxylic beetles, owing to weak numerical responses, may so far have played a minor role in decomposing the vast quantities of dead wood left by the moth outbreak.

  18. Spatial patterns in abundance, taxonomic composition and carbon biomass of nano- and microphytoplankton in Subarctic and Arctic Seas

    Science.gov (United States)

    Crawford, David W.; Cefarelli, Adrián O.; Wrohan, Ian A.; Wyatt, Shea N.; Varela, Diana E.

    2018-03-01

    In the summers of 2007 and 2008, we studied assemblages of nano- and microphytoplankton from the subsurface chlorophyll maximum (SCM) across five broad oceanographic domains in the seas surrounding northern North America. These domains are the eastern Subarctic North Pacific (ESNP), Bering and Chukchi Seas (BE-CH), Beaufort Sea and Canada Basin (BS-CB), Canadian Arctic Archipelago (CAA), and Baffin Bay and Labrador Sea (BB-LS). Average abundance and total carbon biomass (C) of phytoplankton (>2 μm) varied ∼10-fold and ∼20-fold, respectively, across the five domains. In the BE-CH, CAA and BB-LS, diatoms averaged 35-70% and dinoflagellates 11-45% of total phytoplankton C (>2 μm), whereas in the ESNP and BS-CB, unidentified flagellates/coccoids (2-8 μm) represented a greater proportion of total C (27% and 39% respectively) than in the other domains. In the BE-CH and BB-LS, phytoplankton C (>2 μm) was dominated by dinoflagellates of the genus Gymnodinium, centric diatoms including Thalassiosira spp. and Chaetoceros spp., unidentified flagellates/coccoids (2-8 μm), and cryptomonads. In contrast, diatoms such as Thalassiosira spp. and its resting spores dominated C in the CAA, with dinoflagellates being less significant than in the BE-CH and BB-LS. Unidentified flagellates/coccoids (2-8 μm), Gymnodinium spp., and cryptomonads dominated in the ESNP, and particularly in the BS-CB, where diatoms contributed only 18% of the very low levels of total phytoplankton C (>2 μm). Phytoplankton C (>2 μm) to chlorophyll a ratios (phyto C:chl a) averaged only 31 g C g chl a-1 in the oligotrophic BS-CB domain, and 51-150 g C g chl a-1 in the other domains, whereas ratios of biogenic silica to phytoplankton C (>2 μm) (bSi:phyto C) were lowest in the eastern domains. Estimates of phytoplankton C were highly sensitive to the choice of C to cell volume equations (C:vol) adopted in the calculations, particularly in diatom-rich areas. This study highlights how diatoms and

  19. Late Holocene climate and chemical change at high latitudes: case studies from contaminated sites in subarctic and arctic Canada

    Science.gov (United States)

    Galloway, Jennifer M.; Cooney, Darryl; Crann, Carley; Falck, Hendrik; Howell, Dana; Jamieson, Heather; Macumber, Andrew; Nasser, Nawaf; Palmer, Michael; Patterson, R. Timothy; Parsons, Michael; Roe, Helen M.; Sanei, Hamed; Spence, Christopher; Stavinga, Drew; Swindles, Graeme T.

    2015-04-01

    Climate variability is occurring at unprecedented rates in northern regions of the Earth, yet little is known about the nature of this variability or its influence on chemical cycling in the environment, particularly in areas with a legacy of contamination from past resource development. We use a paleolimnological approach to reconstruct climate and chemical change over centuries and millennia at two sites in the mineral-rich Slave Geologic Province in Northern Canada heavily impacted by gold mining. Such an approach is necessary to define the cumulative effects of climate change on metal loading and can be used to define anthropogenic release of contaminants to support policy and regulation due to a paucity of long-term monitoring data. The Seabridge Gold Inc. Courageous Lake project is a gold exploration project 240 km north of Yellowknife in the central Northwest Territories, Arctic Canada. Mining operations took place within the claim area at the Tundra (1964-1968) and Salmita (1983-1987) mines. Giant Mine is located in the subarctic near the City of Yellowknife and mining at this site represents the longest continuous gold mining operation in Canada (1938 to 2002). Due to the refractory mineralogy of ore, gold was extracted from arsenopyrite by roasting, which resulted in release of substantial quantities of highly toxic arsenic trioxide to the environment. Arsenic (As) is also naturally elevated at these sites due its occurrence in Yellowknife Supergroup greenstone belts and surficial geologic deposits. To attempt to distinguish between geogenic and anthropogenic sources of As and characterize the role of climate change on metalloid mobility we used a freeze coring technology to capture lake sediments from the properties. Sediments were analyzed for sedimentary grain size and bulk geochemistry using ICP-MS to reconstruct climate and chemical change. Micropaleontological analyses are on-going. Interpretations of the physical, chemical, and biological archive

  20. Responses of fungal root colonization, plant cover and leaf nutrients to long-term exposure to elevated atmospheric CO2 and warming in a subarctic birch forest understory

    DEFF Research Database (Denmark)

    Olsrud, Maria; Carlsson, Bengt Å.; Svensson, Brita M.

    2010-01-01

    Responses of the mycorrhizal fungal community in terrestrial ecosystems to global change factors are not well understood. However, virtually all land plants form symbiotic associations with mycorrhizal fungi, with approximately 20% of the plants' net primary production transported down...... by mycorrhizal and other root-associated fungi to global change factors of all the fungal types studied could have broad implications for plant community structure and biogeochemistry of subarctic ecosystems....

  1. Pristine Arctic: Background mapping of PAHs, PAH metabolites and inorganic trace elements in the North-Atlantic Arctic and sub-Arctic coastal environment

    Energy Technology Data Exchange (ETDEWEB)

    Jörundsdóttir, Hrönn Ólína, E-mail: hronn.o.jorundsdottir@matis.is [Matis Ltd., Icelandic Food and Biotech R and D, Vinlandsleid 12, 113 Reykjavik (Iceland); Jensen, Sophie [Matis Ltd., Icelandic Food and Biotech R and D, Vinlandsleid 12, 113 Reykjavik (Iceland); Hylland, Ketil; Holth, Tor Fredrik [Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo (Norway); Gunnlaugsdóttir, Helga [Matis Ltd., Icelandic Food and Biotech R and D, Vinlandsleid 12, 113 Reykjavik (Iceland); Svavarsson, Jörundur [University of Iceland, Department of Life and Environmental Sciences, Askja - Natural Science Building, Sturlugata 7, 101 Reykjavík (Iceland); Ólafsdóttir, Ásdís [The University of Iceland´s Research Centre in Sudurnes, Gardvegi 1, 245 Sandgerdi (Iceland); El-Taliawy, Haitham [Matis Ltd., Icelandic Food and Biotech R and D, Vinlandsleid 12, 113 Reykjavik (Iceland); Rigét, Frank; Strand, Jakob [Department of Bioscience, Arctic Research Centre, Aarhus University, Frederiksborgvej 399, PO Box 358, DK-4000 Roskilde (Denmark); Nyberg, Elisabeth; Bignert, Anders [Swedish Museum of Natural History, P.O. Box 50007, 104 05 Stockholm (Sweden); Hoydal, Katrin S. [The Faroese Environment Agency, Traðagøta 38, P.O. Box 2048, FO-165 Argir, the Faroe Islands (Faroe Islands); Halldórsson, Halldór Pálmar [The University of Iceland´s Research Centre in Sudurnes, Gardvegi 1, 245 Sandgerdi (Iceland)

    2014-09-15

    As the ice cap of the Arctic diminishes due to global warming, the polar sailing route will be open larger parts of the year. These changes are likely to increase the pollution load on the pristine Arctic due to large vessel traffic from specific contaminant groups, such as polycyclic aromatic hydrocarbons (PAHs). A well-documented baseline for PAH concentrations in the biota in the remote regions of the Nordic Seas and the sub-Arctic is currently limited, but will be vital in order to assess future changes in PAH contamination in the region. Blue mussels (Mytilus edulis) were collected from remote sites in Greenland, Iceland, the Faroe Islands, Norway and Sweden as well as from urban sites in the same countries for comparison. Cod (Gadus morhua) was caught north of Iceland and along the Norwegian coast. Sixteen priority PAH congeners and the inorganic trace elements arsenic, cadmium, mercury and lead were analysed in the blue mussel samples as well as PAH metabolites in cod bile. Σ{sub 16}PAHs ranged from 28 ng/g dry weight (d.w.) (Álftafjörður, NW Iceland) to 480 ng/g d.w. (Ísafjörður, NW Iceland). Mussel samples from Mjóifjörður, East Iceland and Maarmorilik, West Greenland, contained elevated levels of Σ{sub 16}PAHs, 370 and 280 ng/g d.w., respectively. Levels of inorganic trace elements varied with highest levels of arsenic in mussels from Ísafjörður, Iceland (79 ng/g d.w.), cadmium in mussels from Mjóifjörður, Iceland (4.3 ng/g d.w.), mercury in mussels from Sørenfjorden, Norway (0.23 ng/g d.w.) and lead in mussels from Maarmorilik, Greenland (21 ng/g d.w.). 1-OH-pyrene was only found above limits of quantification (0.5 ng/mL) in samples from the Norwegian coast, ranging between 44 and 140 ng/ml bile. Generally, PAH levels were low in mussels from the remote sites investigated in the study, which indicates limited current effect on the environment. - Highlights: • Low levels of PAHs in blue mussels from remote areas of the Arctic. • Low

  2. Interannual variations of net community production and air-sea CO2 flux from winter to spring in the western subarctic North Pacific

    International Nuclear Information System (INIS)

    Midorikawa, Takashi; Ogawa, Kan; Nemoto, Kazuhiro; Kamiya, Hitomi; Umeda, Takafumi; Hiraishi, Naotaka; Wada, Akira; Ishii, Masao

    2003-01-01

    The role of spring biological production for the air-sea CO 2 flux was quantified in the Western Subarctic Gyre (48 deg N, 165 deg E), where the vertical profile of temperature revealed the existence of a temperature minimum (Tmin) layer in the North Pacific. The vertical profiles of temperature, salinity, dissolved oxygen, nutrients and dissolved inorganic carbon, DIC, in the upper water column were significantly variable year by year in spring, 1996-2000. Correspondingly, surface seawater at this site in spring was supersaturated with CO 2 in 1997, 1999 and 2000, but was undersaturated in 1996 and 1998. The concentrations of DIC and nutrients in the winter mixed layer were estimated from those in the Tmin layer in spring with a correction for particle decomposition based on the apparent oxygen utilization. The net community production (NCP) and air-sea CO 2 flux from winter to spring were calculated from the vertically integrated deficits of DIC and nutrients in the upper water column between the two seasons. The calculation of the carbon budget indicated large interannual variations of NCP (0-13 mmol/m 2 /d) and CO 2 efflux (4-16 mmol/m 2 /d) for this period. The CO 2 efflux was generally low in the year when NCP was high. The close coupling between biological production and CO 2 efflux suggested the important role of the changes in the mixed-layer depth, as a key process controlling both processes, especially of the timing, so that a decrease in the mixed-layer depth could result in the activation of biological production. The early biological consumption of the surface DIC concentration could shorten the period for acting as a source for atmospheric CO 2 and depress the CO 2 efflux in the Western Subarctic Gyre from winter to spring in 1996 and 1998. On the contrary, in 1997, persistently deep vertical mixing until late spring could suppress the biological activity and give rise to long-lasting CO 2 efflux

  3. Ten-year trends of atmospheric mercury in the high Arctic compared to Canadian sub-Arctic and mid-latitude sites

    Directory of Open Access Journals (Sweden)

    A. S. Cole

    2013-02-01

    Full Text Available Global emissions of mercury continue to change at the same time as the Arctic is experiencing ongoing climatic changes. Continuous monitoring of atmospheric mercury provides important information about long-term trends in the balance between transport, chemistry, and deposition of this pollutant in the Arctic atmosphere. Ten-year records of total gaseous mercury (TGM from 2000 to 2009 were analyzed from two high Arctic sites at Alert (Nunavut, Canada and Zeppelin Station (Svalbard, Norway; one sub-Arctic site at Kuujjuarapik (Nunavik, Québec, Canada; and three temperate Canadian sites at St. Anicet (Québec, Kejimkujik (Nova Scotia and Egbert (Ontario. Five of the six sites examined showed a decreasing trend over this time period. Overall trend estimates at high latitude sites were: −0.9% yr−1 (95% confidence limits: −1.4, 0 at Alert and no trend (−0.5, +0.7 at Zeppelin Station. Faster decreases were observed at the remainder of the sites: −2.1% yr−1 (−3.1, −1.1 at Kuujjuarapik, −1.9% yr−1 (−2.1, −1.8 at St. Anicet, −1.6% yr−1 (−2.4, −1.0 at Kejimkujik and −2.2% yr−1 (−2.8, −1.7 at Egbert. Trends at the sub-Arctic and mid-latitude sites agree with reported decreases in background TGM concentration since 1996 at Mace Head, Ireland, and Cape Point, South Africa, but conflict with estimates showing an increase in global anthropogenic emissions over a similar period. Trends in TGM at the two high Arctic sites were not only less negative (or neutral overall but much more variable by season. Possible reasons for differences in seasonal and overall trends at the Arctic sites compared to those at lower latitudes are discussed, as well as implications for the Arctic mercury cycle. The first calculations of multi-year trends in reactive gaseous mercury (RGM and total particulate mercury (TPM at Alert were also performed, indicating increases from 2002 to 2009

  4. New data on the natural environment of the Middle and Late Neopleistocene interglacial periods in the east of the European Subarctic Region of Russia

    Science.gov (United States)

    Andreicheva, L. N.; Marchenko-Vagapova, T. I.

    2017-11-01

    The data obtained from investigation of the Middle and Late Neopleistocene lake sediments in the European Subarctic Region of Russia are reported. Chirva, Rodionovo (Scklov), Sula (Mikulino), and Byzovaya (Leningrad) sediments were subject to palynological analysis and investigation of particle size distribution and mineral composition. The spore-pollen spectra of the Chirva sediments demonstrate two climatic optima: the lower optimum is dominated by the pollen of Pinus sylvestris and broad-leaved species (up to 10%); the upper optimum is dominated by Picea sp. and Pinus sylvestris, while the pollen of Picea sect. Omorica and broad-leaved species are sporadic. The Rodionovo flora is characterized by a more xerophilous composition relative to the Chirva flora and a higher pollen content of pine, birch, wormseed plants, and wormwood. The climatic optimum of the Sula interglacial is distinguished by boreal vegetation, including spruce, birch, and birch-spruce forests with sparse broad-leaved species. The Byzovaya interstadial is marked by seven stages of changes in the vegetation: from tundra and forest-tundra communities to taiga forests with some broad-leaved species. The natural climatic sedimentation conditions in the Middle and Late Neopleistocene interglacial periods are reconstructed. The mineral composition of sediments was largely formed owing to underlying deposits.

  5. A comparative assessment of heavy metal accumulation in soft parts and byssus of mussels from subarctic, temperate, subtropical and tropical marine environments

    International Nuclear Information System (INIS)

    Szefer, P.; Fowler, S.W.; Ikuta, K.; Osuna, F. Paez; Ali, A.A.; Kim, B.-S.; Fernandes, H.M.; Belzunce, M.-J.; Guterstam, B.; Kunzendorf, H.; Wolowicz, M.; Hummel, H.; Deslous-Paoli, M.

    2006-01-01

    Existing data on metal concentrations in mussels from subarctic, temperate, subtropical and tropical waters were analyzed using multivariate statistics in order to assess regional variations in metal contamination. Potential errors were reduced by only analyzing data from surveys that employed the same protocols, analytical methodologies and analysts. Factor analysis demonstrated that mussels inhabiting extremely contaminated areas (e.g. from Japanese and Swedish metallurgy sources) could be separated from mussels from other contaminated areas, and that metals such as Cd, Pb, Cu and Zn could be used to identify heavily contaminated samples while Co, Fe, Cr and Ni concentrations were good markers for exposure to inputs from different industrial sources. Furthermore byssus, like soft tissue, selectively and sensitively reflects variations of certain metal concentrations in ambient waters and thus serves as a reliable biomonitor for these contaminants in a variety of coastal and estuarine areas. - Byssus of mytilids, like soft tissues can be used as efficient biomonitor for heavy metals in the marine environment

  6. Nineteen-year time-series sediment trap study of Coccolithus pelagicus and Emiliania huxleyi (calcareous nannoplankton) fluxes in the Bering Sea and subarctic Pacific Ocean

    Science.gov (United States)

    Tsutsui, Hideto; Takahashi, Kozo; Asahi, Hirofumi; Jordan, Richard W.; Nishida, Shiro; Nishiwaki, Niichi; Yamamoto, Sumito

    2016-03-01

    Coccolithophore fluxes at two sediment trap stations, Station AB in the Bering Sea and Station SA in the subarctic Pacific Ocean, were studied over a nineteen-year (August 1990-July 2009) interval. Two major species, Coccolithus pelagicus and Emiliania huxleyi, occur at both stations, with Gephyrocapsa oceanica, Umbilicosphaera sibogae, Braarudosphaera bigelowii, and Syracosphaera spp. as minor components. The mean coccolithophore fluxes at Stations AB and SA increased from 28.9×106 m2 d-1 and 61.9×106 m2 d-1 in 1990-1999 to 54.4×106 m2 d-1 and 130.2×106 m2 d-1 in 2002-2009, respectively. Furthermore, in late 1999 to early 2000, there was a significant shift in the most dominant species from E. huxleyi to C. pelagicus. High abundances of E. huxleyi correspond to the positive mode of the Pacific Decadal Oscillation (PDO), while those of C. pelagicus respond to the PDO negative mode and are related to water temperature changes at huxleyi. At both stations the mean seawater temperature in the top 45 m from August to October increased ca. 1 °C with linear recurrence from 1990 to 2008. The coccosphere fluxes after Year 2000 at Stations AB and SA, and the shift in species dominance, may have been influenced by this warming.

  7. The Potential Use of Agroforestry Community Gardens as a Sustainable Import-Substitution Strategy for Enhancing Food Security in Subarctic Ontario, Canada

    Directory of Open Access Journals (Sweden)

    Maren Oelbermann

    2013-09-01

    Full Text Available The high prevalence of food insecurity experienced by northern First Nations partially results from dependence on an expensive import-based food system that typically lacks nutritional quality and further displaces traditional food systems. In the present study, the feasibility of import substitution by Agroforestry Community Gardens (AFCGs as socio-ecologically and culturally sustainable means of enhancing food security was explored through a case study of Fort Albany First Nation in subarctic Ontario, Canada. Agroforestry is a diverse tree-crop agricultural system that has enhanced food security in the tropics and subtropics. Study sites were selected for long-term agroforestry research to compare Salix spp. (willow-dominated AFCG plots to a “no tree” control plot in Fort Albany. Initial soil and vegetative analysis revealed a high capacity for all sites to support mixed produce with noted modifications, as well as potential competitive and beneficial willow-crop interactions. It is anticipated that inclusion of willow trees will enhance the long-term productive capacity of the AFCG test plots. As an adaptable and dynamic system, AFCGs have potential to act as a more reliable local agrarian system and a refuge for culturally significant plants in high-latitude First Nation socio-ecological systems, which are particularly vulnerable to rapid cultural, climatic, and ecological change.

  8. New parasites and predators follow the introduction of two fish species to a subarctic lake: implications for food-web structure and functioning

    Science.gov (United States)

    Amundsen, Per-Arne; Lafferty, Kevin D.; Knudsen, Rune; Primicerio, Raul; Kristoffersen, Roar; Klemetsen, Anders; Kuris, Armand M.

    2012-01-01

    Introduced species can alter the topology of food webs. For instance, an introduction can aid the arrival of free-living consumers using the new species as a resource, while new parasites may also arrive with the introduced species. Food-web responses to species additions can thus be far more complex than anticipated. In a subarctic pelagic food web with free-living and parasitic species, two fish species (arctic charr Salvelinus alpinus and three-spined stickleback Gasterosteus aculeatus) have known histories as deliberate introductions. The effects of these introductions on the food web were explored by comparing the current pelagic web with a heuristic reconstruction of the pre-introduction web. Extinctions caused by these introductions could not be evaluated by this approach. The introduced fish species have become important hubs in the trophic network, interacting with numerous parasites, predators and prey. In particular, five parasite species and four predatory bird species depend on the two introduced species as obligate trophic resources in the pelagic web and could therefore not have been present in the pre-introduction network. The presence of the two introduced fish species and the arrival of their associated parasites and predators increased biodiversity, mean trophic level, linkage density, and nestedness; altering both the network structure and functioning of the pelagic web. Parasites, in particular trophically transmitted species, had a prominent role in the network alterations that followed the introductions.

  9. Multi-proxy Paleoclimate and CO2 Reconstruction from the Latest Middle Eocene Sedimentary Fill of a Subarctic Kimberlitic Maar Crater

    Science.gov (United States)

    Reyes, A. V.; Wolfe, A. P.; Royer, D. L.; Greenwood, D. R.; Tierney, J. E.; Doria, G.; Gagen, M. H.; Siver, P.; Westgate, J.

    2016-12-01

    Eocene paleoclimate reconstructions are rarely accompanied by parallel estimates of CO2, complicating assessment of the equilibrium climate responses to CO2. We reconstruct temperature, precipitation, and CO2 from latest middle Eocene ( 38 Myrs ago) peats in subarctic Canada, preserved in sediments that record infilling of a kimberlite pipe maar crater. Mutual climatic range analyses of pollen, together with oxygen isotope analyses of a-cellulose from unpermineralized wood and inferenecs from branched glycerol diakyl glycerol tetraethers (GDGTs), reveal a high-latitude humid-temperate forest ecosystem with mean annual temperatures (MATs) >17 °C warmer than present, mean coldest month temperatures above 0 °C, and mean annual precipitation 4x present. Metasequoia stomatal indices and gas-exchange modeling produce median CO2 concentrations of 634 and 432 ppm, respectively, with a consensus median estimate of 494 ppm. Reconstructed MATs are >6 °C warmer than those produced by Eocene climate models forced at 560 ppm CO2, underscoring the capacity for exceptional polar amplification of warming and hydrological intensification under relatively modest CO2 concentrations, once both fast and slow feedbacks become expressed.

  10. A comparative assessment of heavy metal accumulation in soft parts and byssus of mussels from subarctic, temperate, subtropical and tropical marine environments

    Energy Technology Data Exchange (ETDEWEB)

    Szefer, P. [Department of Food Sciences, Medical University of Gdansk, Al. Gen. J. Hallera 107, PL 80-416 Gdansk (Poland)]. E-mail: pszef@amg.gda.pl; Fowler, S.W. [IAEA Marine Environment Laboratory, 4 Quai Antoine 1er, MC-98000 (Monaco); Ikuta, K. [Laboratory of Aquatic Environment and Ecology, Department of Fisheries, Faculty of Agriculture, Miyazaki University, 889-21 Miyazaki (Japan); Osuna, F. Paez [Institute of Marine Sciences and Limnology, Mazatlan Station, National Autonomous University of Mexico, Mazatlan 82000, Sinaloa (Mexico); Ali, A.A. [Faculty of Science, Arts and Education, University of Aden, PO Box 6014, Khormaksar, Aden (Yemen); Kim, B.-S. [School of Earth and Environmental Science, Seoul National University, 56-1 Shillimdong, 151-742 (Korea, Republic of); Fernandes, H.M. [Instituto de Radioprotecao e Dosimetria, Cz. Postal 37 750 - CEP: 22642-970, Rio de Janeiro (Brazil); Belzunce, M.-J. [Instituto Tecnnologico Pesquero y Alimentario, Dpto de Oceanografia y Medio Ambiente Marino, Herrera Kaia, Portualdea z/g, 20110 Pasaia (Gipuzkoa) (Spain); Guterstam, B. [Stensund Ecological Center, 61991 Trosa, Sweden and Global Water Partnership Secretariat, Hantverkargatan 5, SE-112 21 Stockholm (Sweden); Kunzendorf, H. [Gamma Dating Center (GDC), Institute of Geography, University of Copenhagen, Oster Voldgage 10 DK-1350 Copenhagen K (Denmark); Wolowicz, M. [Laboratory of Estuarine Ecology, Institute of Oceanography, University of Gdansk, Al. Pilsudskiego 46, 81-378, Gdynia (Poland); Hummel, H. [Centre for Estuarine and Marine Ecology, Netherlands Institute of Ecology, Korringaweg 7, 4401 NT Yerseke (Netherlands); Deslous-Paoli, M. [IFREMER, Unite Ecologie Conchylicole, 1, rue Jean Vilar, 34200 Sete (France)

    2006-01-15

    Existing data on metal concentrations in mussels from subarctic, temperate, subtropical and tropical waters were analyzed using multivariate statistics in order to assess regional variations in metal contamination. Potential errors were reduced by only analyzing data from surveys that employed the same protocols, analytical methodologies and analysts. Factor analysis demonstrated that mussels inhabiting extremely contaminated areas (e.g. from Japanese and Swedish metallurgy sources) could be separated from mussels from other contaminated areas, and that metals such as Cd, Pb, Cu and Zn could be used to identify heavily contaminated samples while Co, Fe, Cr and Ni concentrations were good markers for exposure to inputs from different industrial sources. Furthermore byssus, like soft tissue, selectively and sensitively reflects variations of certain metal concentrations in ambient waters and thus serves as a reliable biomonitor for these contaminants in a variety of coastal and estuarine areas. - Byssus of mytilids, like soft tissues can be used as efficient biomonitor for heavy metals in the marine environment.

  11. CNP stoichiometry of a lipid-synthesising zooplankton, Calanus finmarchicus, from winter to spring bloom in a sub-Arctic sound

    Science.gov (United States)

    Aubert, A. B.; Svensen, C.; Hessen, D. O.; Tamelander, T.

    2013-02-01

    The aim of this study was to investigate the seasonal stoichiometry of the high-latitude lipid-synthesising copepod Calanus finmarchicus and assess how this would affect dietary demands with season, ontogeny and lipid storage. C:N:P ratios in different stages (adults, copepodite V and IV), in eggs and faecal pellets as well as in bulk food (seston) was analysed in a sub-Arctic Norwegian sound (69° 47'N, 19° 19'E) from late February to mid-May 2009. The period covered the phytoplankton bloom and was divided into four sequences of the bloom based on chl a and seston C:chl a ratio variations. The calculation of the somatic elemental C:N and C:P body ratios (without the lipid storage) indicates that nearly homeostatic control in C. finmarchicus is maintained in somatic tissues within stages, while not if the lipid storage pool is included. Nutrient limitation was assessed calculating threshold elemental ratios based on the somatic body ratios and for different sets of assimilation efficiencies, and indicated a predominant C limitation that may reflect demands for lipid storage. The results suggest that stoichiometric composition and demands in such high-latitude, lipid-storing species strongly depend on stage and season, and the large contribution of storage lipids highlights the need for a two-compartment approach for lipid-synthesising species, with different dietary requirements for somatic growth and for lipid storage.

  12. Seasonal calcareous nannoplankton and other biogenic particle fluxes for 1990-2009: twenty-year long records from the central subarctic Pacific Ocean and the Bering Sea

    Science.gov (United States)

    Takahashi, Kozo; Tsutsui, Hideto

    2017-04-01

    Time-series sediment traps were deployed for nearly 20 years (1990-2009) at two long-term locations: Station SA (49°N, 174°W, trap depth 4,800 m, water depth 5,400 m) in the central subarctic Pacific, and Station AB (53.5°N, 177°W, trap depth 3,200 m, water depth 3,800 m) in the southern Bering Sea. Among many biogenic particles, calcareous nannoplankton represented nearly half or more of the entire calcium carbonate fluxes of the regions. Dominant taxa include Coccolithus pelagicus and Emiliania huxleyi. The flux maxima of the former taxon occurred twice a year during June and October-November, whereas that of the latter taxon only occurred primarily once a year in November at both stations, indicating environmental preferences of the taxa. Among many environmental conditions, the fluxes of Emiliania huxleyi showed strong correlations with both water temperatures above 45 m depth and air temperatures (these parameters taken with one-month lag [earlier values] considering sinking time of ca. a month to the respective trap depths). Coccolithus pelagicus, on the other hand, showed lower values in the correlation with temperatures (Tsutsui et al., 2016), indicating that this taxon is somewhat more dependent on other factors such as nutrients compared to those of E. huxleyi. The timings of the seasonal flux maxima of calcareous nannoplankton are quite different from and later than those of other taxonomic groups such as diatoms and silicoflagellates. The primary seasonal flux maxima of diatoms and silicoflagellates, for example, occurred in May, a month earlier than the June maximum of C. pelagicus, and secondary seasonal flux maxima occurred in August, 2-3 months earlier than those of calcareous nannoplankton at both stations, based on 8 year flux records for diatoms (Onodera and Takahashi, 2009) and 4 year records for silicoflagellates (Onodera and Takahashi, 2012). By examining seasonal changes of nitrate and phosphate concentrations above 50 m depth from ERDDAP

  13. Impact of Euro-Canadian agrarian practices: in search of sustainable import-substitution strategies to enhance food security in subarctic Ontario, Canada.

    Science.gov (United States)

    Spiegelaar, Nicole F; Tsuji, Leonard J S

    2013-01-01

    In Canada, food insecurity exists among Aboriginal (Inuit, Metis and First Nations) people living in remote northern communities, in part, because of their reliance on the industrialized, import-based food system. Local food production as a substitute to imports would be an adaptive response, but enhancement of food security via food localization requires reflection on previous failings of conventional agricultural strategies so that informed decisions can be made. In light of potential reintroduction of local food production in remote First Nations communities, we investigated the cultural, social and ecological effects of a 20th century, Euro-Canadian agrarian settlement on the food system of a subarctic First Nation; this will act as the first step in developing a more sustainable local food program and enhancing food security in this community. To investigate the socio-cultural impacts of the Euro-Canadian agrarian initiative on the food system of Fort Albany First Nation, purposive, semi-directive interviews were conducted with elders and other knowledgeable community members. Interview data were placed into themes using inductive analyses. To determine the biophysical impact of the agrarian initiative, soil samples were taken from one site within the cultivated area and from one site in an undisturbed forest area. Soil properties associated with agricultural use and productivity were assessed. To compare the means of a given soil property between the sites, one-tailed t-tests were employed. Vegetative analysis was conducted in both sites to assess disturbance. According to the interviewees, prior to the agrarian initiative, First Nation families harvested wild game and fish, and gathered berries as well as other forms of vegetation for sustenance. With the introduction of the residential school and agrarian initiative, traditional food practices were deemed inadequate, families were forced to work and live in the settlement (becoming less reliant on

  14. Effects of short term and long term soil warming on ecosystem phenology of a sub-arctic grassland: an NDVI-based approach

    Science.gov (United States)

    Leblans, Niki; Sigurdsson, Bjarni D.; Janssens, Ivan A.

    2014-05-01

    % greening was advanced by 23 days at +5°C and by 32 days at +10°C Ts. However, no difference in the date of maximum greening or in the onset of senescence occurred. In contrast, in the long-term warmed grassland, the start of the growing season was not affected by Ts and the 50% greening point occurred only 10 days earlier at +5°C and 15 days earlier at +10°C Ts. However, the timing of maximum greening was advanced by 19 days at +5°C and even by 32 days at +10°C Ts. Again, the onset of senescence did not change with Ts. Significant Ts effects on ecosystem phenology of subarctic grasslands only occurred at warming of 5°C or higher. This study also demonstrates that short-term Ts effects on ecosystem phenology are not necessarily good predictors for long-term changes in sub-arctic grasslands. In the short-term (5 years warming), soil warming induced an early onset of the growing season, which was later compensated by faster greening on colder soils, so that maximum greenness was reached simultaneously irrespective of Ts. In contrast, the long-term Ts warming did not induce earlier onset of the growing season, but it led to faster greening on warm soils, which again led to an advance in timing of maximum greenness. This difference between short- and long-term responses in phenology might be caused by either phenotypic plasticity (acclimation) or by a genetic selection (evolution) of the grass populations where the warming has been ongoing for centuries. Such processes are at present not included in modelling predictions of climate change responses of natural ecosystems, but may offer important negative feedback mechanisms to warming which will reduce its effects.

  15. Growing season CH4 and N2O fluxes from a subarctic landscape in northern Finland; from chamber to landscape scale

    Science.gov (United States)

    Dinsmore, Kerry J.; Drewer, Julia; Levy, Peter E.; George, Charles; Lohila, Annalea; Aurela, Mika; Skiba, Ute M.

    2017-02-01

    Subarctic and boreal emissions of CH4 are important contributors to the atmospheric greenhouse gas (GHG) balance and subsequently the global radiative forcing. Whilst N2O emissions may be lower, the much greater radiative forcing they produce justifies their inclusion in GHG studies. In addition to the quantification of flux magnitude, it is essential that we understand the drivers of emissions to be able to accurately predict climate-driven changes and potential feedback mechanisms. Hence this study aims to increase our understanding of what drives fluxes of CH4 and N2O in a subarctic forest/wetland landscape during peak summer conditions and into the shoulder season, exploring both spatial and temporal variability, and uses satellite-derived spectral data to extrapolate from chamber-scale fluxes to a 2 km × 2 km landscape area.From static chamber measurements made during summer and autumn campaigns in 2012 in the Sodankylä region of northern Finland, we concluded that wetlands represent a significant source of CH4 (3.35 ± 0.44 mg C m-2 h-1 during the summer campaign and 0.62 ± 0.09 mg C m-2 h-1 during the autumn campaign), whilst the surrounding forests represent a small sink (-0.06 ± zero across both ecosystems.We found a weak negative relationship between CH4 emissions and water table depth in the wetland, with emissions decreasing as the water table approached and flooded the soil surface and a positive relationship between CH4 emissions and the presence of Sphagnum mosses. Temperature was also an important driver of CH4 with emissions increasing to a peak at approximately 12 °C. Little could be determined about the drivers of N2O emissions given the small magnitude of the fluxes.A multiple regression modelling approach was used to describe CH4 emissions based on spectral data from PLEIADES PA1 satellite imagery across a 2 km × 2 km landscape. When applied across the whole image domain we calculated a CH4 source of 2.05 ± 0.61 mg C m-2 h-1. This was

  16. Diurnal variation in the coupling of photosynthetic electron transport and carbon fixation in iron-limited phytoplankton in the NE subarctic Pacific

    Science.gov (United States)

    Schuback, Nina; Flecken, Mirkko; Maldonado, Maria T.; Tortell, Philippe D.

    2016-02-01

    Active chlorophyll a fluorescence approaches, including fast repetition rate fluorometry (FRRF), have the potential to provide estimates of phytoplankton primary productivity at an unprecedented spatial and temporal resolution. FRRF-derived productivity rates are based on estimates of charge separation in reaction center II (ETRRCII), which must be converted into ecologically relevant units of carbon fixation. Understanding sources of variability in the coupling of ETRRCII and carbon fixation provides physiological insight into phytoplankton photosynthesis and is critical for the application of FRRF as a primary productivity measurement tool. In the present study, we simultaneously measured phytoplankton carbon fixation and ETRRCII in the iron-limited NE subarctic Pacific over the course of a diurnal cycle. We show that rates of ETRRCII are closely tied to the diurnal cycle in light availability, whereas rates of carbon fixation appear to be influenced by endogenous changes in metabolic energy allocation under iron-limited conditions. Unsynchronized diurnal oscillations of the two rates led to 3.5-fold changes in the conversion factor between ETRRCII and carbon fixation (Kc / nPSII). Consequently, diurnal variability in phytoplankton carbon fixation cannot be adequately captured with FRRF approaches if a constant conversion factor is applied. Utilizing several auxiliary photophysiological measurements, we observed that a high conversion factor is associated with conditions of excess light and correlates with the increased expression of non-photochemical quenching (NPQ) in the pigment antenna, as derived from FRRF measurements. The observed correlation between NPQ and Kc / nPSII requires further validation but has the potential to improve estimates of phytoplankton carbon fixation rates from FRRF measurements alone.

  17. Foliar pH as a new plant trait: can it explain variation in foliar chemistry and carbon cycling processes among subarctic plant species and types?

    Science.gov (United States)

    Cornelissen, J H C; Quested, H M; van Logtestijn, R S P; Pérez-Harguindeguy, N; Gwynn-Jones, D; Díaz, S; Callaghan, T V; Press, M C; Aerts, R

    2006-03-01

    Plant traits have become popular as predictors of interspecific variation in important ecosystem properties and processes. Here we introduce foliar pH as a possible new plant trait, and tested whether (1) green leaf pH or leaf litter pH correlates with biochemical and structural foliar traits that are linked to biogeochemical cycling; (2) there is consistent variation in green leaf pH or leaf litter pH among plant types as defined by nutrient uptake mode and higher taxonomy; (3) green leaf pH can predict a significant proportion of variation in leaf digestibility among plant species and types; (4) leaf litter pH can predict a significant proportion of variation in leaf litter decomposability among plant species and types. We found some evidence in support of all four hypotheses for a wide range of species in a subarctic flora, although cryptogams (fern allies and a moss) tended to weaken the patterns by showing relatively poor leaf digestibility or litter decomposability at a given pH. Among seed plant species, green leaf pH itself explained only up to a third of the interspecific variation in leaf digestibility and leaf litter up to a quarter of the interspecific variation in leaf litter decomposability. However, foliar pH substantially improved the power of foliar lignin and/or cellulose concentrations as predictors of these processes when added to regression models as a second variable. When species were aggregated into plant types as defined by higher taxonomy and nutrient uptake mode, green-specific leaf area was a more powerful predictor of digestibility or decomposability than any of the biochemical traits including pH. The usefulness of foliar pH as a new predictive trait, whether or not in combination with other traits, remains to be tested across more plant species, types and biomes, and also in relation to other plant or ecosystem traits and processes.

  18. Responses of microbial tolerance to heavy metals along a century-old metal ore pollution gradient in a subarctic birch forest.

    Science.gov (United States)

    Rousk, Johannes; Rousk, Kathrin

    2018-05-07

    Heavy metals are some of the most persistent and potent anthropogenic environmental contaminants. Although heavy metals may compromise microbial communities and soil fertility, it is challenging to causally link microbial responses to heavy metals due to various confounding factors, including correlated soil physicochemistry or nutrient availability. A solution is to investigate whether tolerance to the pollutant has been induced, called Pollution Induced Community Tolerance (PICT). In this study, we investigated soil microbial responses to a century-old gradient of metal ore pollution in an otherwise pristine subarctic birch forest generated by a railway source of iron ore transportation. To do this, we determined microbial biomass, growth, and respiration rates, and bacterial tolerance to Zn and Cu in replicated distance transects (1 m-4 km) perpendicular to the railway. Microbial biomass, growth and respiration rates were stable across the pollution gradient. The microbial community structure could be distinguished between sampled distances, but most of the variation was explained by soil pH differences, and it did not align with distance from the railroad pollution source. Bacterial tolerance to Zn and Cu started from background levels at 4 km distance from the pollution source, and remained at background levels for Cu throughout the gradient. Yet, bacterial tolerance to Zn increased 10-fold 100 m from the railway source. Our results show that the microbial community structure, size and performance remained unaffected by the metal ore exposure, suggesting no impact on ecosystem functioning. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Combined effects of environmental disturbance and climate warming on insect herbivory in mountain birch in subarctic forests: Results of 26-year monitoring.

    Science.gov (United States)

    Kozlov, M V; Zverev, V; Zvereva, E L

    2017-12-01

    Both pollution and climate affect insect-plant interactions, but the combined effects of these two abiotic drivers of global change on insect herbivory remain almost unexplored. From 1991 to 2016, we monitored the population densities of 25 species or species groups of insects feeding on mountain birch (Betula pubescens ssp. czerepanovii) in 29 sites and recorded leaf damage by insects in 21 sites in subarctic forests around the nickel-copper smelter at Monchegorsk, north-western Russia. The leaf-eating insects demonstrated variable, and sometimes opposite, responses to pollution-induced forest disturbance and to climate variations. Consequently, we did not discover any general trend in herbivory along the disturbance gradient. Densities of eight species/species groups correlated with environmental disturbance, but these correlations weakened from 1991 to 2016, presumably due to the fivefold decrease in emissions of sulphur dioxide and heavy metals from the smelter. The densities of externally feeding defoliators decreased from 1991 to 2016 and the densities of leafminers increased, while the leaf roller densities remained unchanged. Consequently, no overall temporal trend in the abundance of birch-feeding insects emerged despite a 2-3°C elevation in spring temperatures. Damage to birch leaves by insects decreased during the observation period in heavily disturbed forests, did not change in moderately disturbed forests and tended to increase in pristine forests. The temporal stability of insect-plant interactions, quantified by the inverse of the coefficient of among-year variations of herbivore population densities and of birch foliar damage, showed a negative correlation with forest disturbance. We conclude that climate differently affects insect herbivory in heavily stressed versus pristine forests, and that herbivorous insects demonstrate diverse responses to environmental disturbance and climate variations. This diversity of responses, in combination with the

  20. tree structural and species diversities in okwangwo forest, cross river

    African Journals Online (AJOL)

    Tersor

    and this can only be possible through a genuine information about ... support biodiversity conservation, and this would ... ecological and environmental changes, reducing ... south-west of the Obudu Plateau and immediately ..... The effect of anthropogenic activities ... pollination, ... biodiversity hotspot in rainforest of Nigeria.

  1. Tree structural and species diversities in Okwangwo Forest, Cross ...

    African Journals Online (AJOL)

    Tree species were grouped into abundance classes. A total of 125 tree species belonging to 36 families and 96 genera were recorded in the area with Margaleffs index of species richness of 2.2754. Most (99) of the tree species encountered were threatened/endangered, 23 species were rare with only 3 tree species ...

  2. multivariate approach to the study of aquatic species diversity

    African Journals Online (AJOL)

    User

    2016-12-02

    Dec 2, 2016 ... Eigen value of the three variables namely; Temperature, pH and Electrical Conductivity ... affect the stream macroinvertebrates (Fornaroli et al., 2016). ... relation to stream land use activities (Tinotenda et al., ... to rotate the multivariate data cloud and extract the ..... community modeling of species distribution.

  3. 1 Species Diversity and Relative Abundance.cdr

    African Journals Online (AJOL)

    Administrator

    from beach seine landings along the central coast during the study period. Landing sites were Winneba, Saltpond and Cape Coast. (Fig. 1). Fish identification was done in the laboratory using manuals (Schneider, 1990;. Kwei & Ofori-Adu, 2005). The identifications were to the family and species levels. Various fish species ...

  4. Life form and species diversity on abandoned croplands, Roggeveld ...

    African Journals Online (AJOL)

    The Roggeveld consists of an island of Mountain Renosterveld (Fynbos biome) surrounded by Succulent Karoo biome vegetation. Since management of abandoned croplands depends on a better understanding of their succession sequences, vegetation recovery on abandoned croplands in the Roggeveld was studied ...

  5. Phylogeny and Species Diversity of Gulf of California Oysters

    Data.gov (United States)

    U.S. Environmental Protection Agency — Dataset of DNA sequence data from two mitochondrial loci (COI and 16S) used to infer the phylogeny of oysters in the genus Ostrea along the Pacific coast of North...

  6. Unrecognized coral species diversity masks differences in functional ecology.

    Science.gov (United States)

    Boulay, Jennifer N; Hellberg, Michael E; Cortés, Jorge; Baums, Iliana B

    2014-02-07

    Porites corals are foundation species on Pacific reefs but a confused taxonomy hinders understanding of their ecosystem function and responses to climate change. Here, we show that what has been considered a single species in the eastern tropical Pacific, Porites lobata, includes a morphologically similar yet ecologically distinct species, Porites evermanni. While P. lobata reproduces mainly sexually, P. evermanni dominates in areas where triggerfish prey on bioeroding mussels living within the coral skeleton, thereby generating asexual coral fragments. These fragments proliferate in marginal habitat not colonized by P. lobata. The two Porites species also show a differential bleaching response despite hosting the same dominant symbiont subclade. Thus, hidden diversity within these reef-builders has until now obscured differences in trophic interactions, reproductive dynamics and bleaching susceptibility, indicative of differential responses when confronted with future climate change.

  7. Fish species diversity and conservation in Beijing and adjacent areas

    OpenAIRE

    Chunguang Zhang; Yahui Zhao; Yingchun Xing; Ruilu Guo; Qing Zhang; Yun Feng; Enyuan Fan

    2011-01-01

    Based on field surveys between 2002 and 2010, and fish collections in the National Zoological Museum, Institute of Zoology, Chinese Academy of Sciences, a total of 93 wild fish species including 12 in-troduced species had been recorded in Beijing and adjacent areas. Eighty five of these species, including some migratory and estuarine fishes, are native to the region. Only 43 native wild species were collected in our field work from 2002 to 2010. Compared with the historical records, nearly 50...

  8. Species diversity of culturable endophytic fungi from Brazilian mangrove forests.

    Science.gov (United States)

    de Souza Sebastianes, Fernanda Luiza; Romão-Dumaresq, Aline Silva; Lacava, Paulo Teixeira; Harakava, Ricardo; Azevedo, João Lúcio; de Melo, Itamar Soares; Pizzirani-Kleiner, Aline Aparecida

    2013-08-01

    This study aimed to perform a comparative analysis of the diversity of endophytic fungal communities isolated from the leaves and branches of Rhizophora mangle, Avicennia schaueriana and Laguncularia racemosa trees inhabiting two mangroves in the state of São Paulo, Brazil [Cananeia and Bertioga (oil spill-affected and unaffected)] in the summer and winter. Three hundred and forty-three fungi were identified by sequencing the ITS1-5.8S-ITS2 region of rDNA. Differences were observed in the frequencies of fungi isolated from the leaves and branches of these three different plant species sampled from the Bertioga oil spill-affected and the oil-unaffected mangrove sites in the summer and winter; these differences indicate a potential impact on fungal diversity in the study area due to the oil spill. The molecular identification of the fungi showed that the fungal community associated with these mangroves is composed of at least 34 different genera, the most frequent of which were Diaporthe, Colletotrichum, Fusarium, Trichoderma and Xylaria. The Shannon and the Chao1 indices [H'(95 %) = 4.00, H'(97 %) = 4.22, Chao1(95 %) = 204 and Chao1(97 %) = 603] indicated that the mangrove fungal community possesses a vast diversity and richness of endophytic fungi. The data generated in this study revealed a large reservoir of fungal genetic diversity inhabiting these Brazilian mangrove forests and highlighted substantial differences between the fungal communities associated with distinct plant tissues, plant species, impacted sites and sampling seasons.

  9. A Comparative Study of Species Diversity of Migrant Birds Between ...

    African Journals Online (AJOL)

    stop migration. Despite Hadejia-Nguru Wetlands (Ramsar site) being an important wintering ground for migratory birds, little is known about the diversity while density is completely lacking. This study assessed the status of migratory birds in the ...

  10. a comparative study of species diversity of migrant birds between

    African Journals Online (AJOL)

    A.S RINGIM

    ABSTRACT. Among the most complex and fascinating behaviour in birds is their long, non-stop migration. Despite Hadejia-Nguru Wetlands (Ramsar site) being an important wintering ground for migratory birds, little is known about the diversity while density is completely lacking. This study assessed the status of migratory ...

  11. Prospects of molecular markers in Fusarium species diversity

    DEFF Research Database (Denmark)

    Nayaka, S. Chandra; Wulff, Ednar Gadelha; Udayashankar, A.C.

    2011-01-01

    focuses of various molecular-based techniques employed to study the diversity of Fusarium species causing diseases in major food crops. An introduction of fusarial diseases and their mycotoxins and molecular-marker-based methods for detection introduce the concept of marker application. Various well...... for generation of probes and their use in phylogeny of Fusarium spp. are also presented. The concluding part emphasizes the value of molecular markers for assessing genetic variability and reveals that molecular tools are indispensable for providing information not only of one Fusarium species but on whole......-known molecular techniques such as random amplified polymorphic DNA, amplification fragment length polymorphism, etc. to more modern ones such as DNA microarrays, DNA barcoding, and pyrosequencing and their application form the core of the review. Target regions in the genome which can be potential candidates...

  12. Determinants of orchid species diversity in Latin America

    Czech Academy of Sciences Publication Activity Database

    Štípková, Zuzana; Traxmandlová, Iva; Kindlmann, Pavel

    2016-01-01

    Roč. 16, č. 2 (2016), s. 293-297 ISSN 1409-3871 R&D Projects: GA MŠk(CZ) LO1415; GA ČR GB14-36098G Institutional support: RVO:67179843 Keywords : altitude * habitat diversity * species-area relationship Subject RIV: EF - Botanics

  13. Towards conserving regional mammalian species diversity: a case ...

    African Journals Online (AJOL)

    1995-03-03

    Mar 3, 1995 ... Species richness maps were derived for the Transvaal region from two different databases, namely a primary point database based on ... of biological diversity is internationally supported, there is no agreement on the ..... example is that of the Rodentia. where greatest species diver- sity. based on survey ...

  14. Detection of species diversity of arbuscular mycorrhizal fungi (AMF ...

    African Journals Online (AJOL)

    Arbuscular-mycorhizal fungi (AMF) from melon plants grown in Van province, were studied by nested-PCR method to establish colonization ratio of related fungi in plants and to detect the fungi at species level. From 10 different locations, a total of 100 soil samples were taken from rhizosphere area of melon plants.

  15. Determinants of orchid species diversity in world islands

    Czech Academy of Sciences Publication Activity Database

    Traxmandlová, Iva; Ackerman, J. D.; Tremblay, R. L.; Roberts, D.L.; Štípková, Zuzana; Kindlmann, Pavel

    2018-01-01

    Roč. 217, č. 1 (2018), s. 12-15 ISSN 0028-646X R&D Projects: GA MŠk(CZ) LO1415; GA ČR GB14-36098G Institutional support: RVO:86652079 Keywords : habitat diversity * island biogeography * latitude * Orchidaceae * species richness * species–area relationship Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 7.330, year: 2016

  16. Species diversity in the Antrodia crassa group (Polyporales, Basidiomycota)

    Czech Academy of Sciences Publication Activity Database

    Spirin, V.; Runnel, K.; Vlasák, Josef; Miettinen, O.; Pöldmaa, K.

    2015-01-01

    Roč. 119, č. 12 (2015), s. 1291-1310 ISSN 1878-6146 Institutional support: RVO:60077344 Keywords : Host specificity * Wood-inhabiting fungi * Taxonomy Subject RIV: EF - Botanics Impact factor: 2.244, year: 2015

  17. Loss of Plant Species Diversity Reduces Soil Erosion Resistance

    NARCIS (Netherlands)

    Berendse, F.; Ruijven, van J.; Jongejans, E.; Keesstra, S.D.

    2015-01-01

    In many estuarine areas around the world, the safety of human societies depends on the functioning of embankments (dikes) that provide protection against river floods and storm tides. Vegetation on land-side slopes protects these embankments from erosion by heavy rains or overtopping waves. We

  18. Species diversity variations in Neogene deep-sea benthic

    Indian Academy of Sciences (India)

    Some species of benthic foraminifera are sensitive to changes in water mass properties whereas others are sensitive to organic fluxes and deep-sea oxygenation. Benthic faunal diversity has been found closely linked to food web, bottom water oxygen levels, and substrate and water mass stability. The present study is ...

  19. Vegetation and Species Diversity in the Northern Sector of Eastern ...

    African Journals Online (AJOL)

    User

    glaucus showed the highest presence estimates among annuals (P = 38.3%, 31.7% ... the most diverse group followed by group A and C in the present study. ... vegetation into two groups: ephemerals and ... their life are dependent on the chance .... Nomenclature, identification and floristic ... variables, on the other hand.

  20. a comparative study of species diversity of migrant birds between

    African Journals Online (AJOL)

    A.S RINGIM

    assessed the status of migratory birds in the wetland's Protected Areas (PAs) and Unprotected. Areas (UPAs). A total of ..... history due to impact of anthropogenic activities ... research. Our sincere gratitude to Harry. Hanson Jr., Ibrahim Dala and Musa Likori for their field ... Impacts of disturbance from construction work on the ...

  1. Tree species Diversity in the Department of Forest Resources ...

    African Journals Online (AJOL)

    An inventory of trees (>10cm diameter at breast height (dbh)) growing within the premises (~1.2ha) of the Department of Forest Resources Management (DFRM), University of Ibadan, Nigeria, was conducted as a case study of the species quality (richness and diversity) and quantity (volume) found on the University campus.

  2. The effects of island ontogeny on species diversity and phylogeny

    NARCIS (Netherlands)

    Valente, Luis M.; Etienne, Rampal S.; Phillimore, Albert B.

    2014-01-01

    A major goal of island biogeography is to understand how island communities are assembled over time. However, we know little about the influence of variable area and ecological opportunity on island biotas over geological time-scales. Islands have limited life spans, and it has been posited that

  3. Species diversity and activity of parasitoids of the sweetpotato ...

    African Journals Online (AJOL)

    The species range, activity and relative abundance of parasitoids attacking the sweetpotato butterfly, Acraea acerata Hew. (Lepidoptera: Nymphalidae) in Uganda was investigated. Samples of eggs and larvae of the sweetpotato butterfly were collected from some of the major sweetpotato growing districts of Uganda to ...

  4. Species diversity variations in Neogene deep-sea benthic ...

    Indian Academy of Sciences (India)

    early Miocene Climatic Optimum (∼17.2–16.4 Ma) followed by a decrease during 16.4–13 Ma ... The benthic foraminiferal populations and diversity at Hole 730A .... counted to calculate percentages. ..... Findlater J 1971 Monthly mean airflow at low levels over ... mass stratification in the northeastern Indian Ocean;.

  5. High-resolution digital mapping of soil organic carbon in permafrost terrain using machine learning: a case study in a sub-Arctic peatland environment

    Science.gov (United States)

    Siewert, Matthias B.

    2018-03-01

    Soil organic carbon (SOC) stored in northern peatlands and permafrost-affected soils are key components in the global carbon cycle. This article quantifies SOC stocks in a sub-Arctic mountainous peatland environment in the discontinuous permafrost zone in Abisko, northern Sweden. Four machine-learning techniques are evaluated for SOC quantification: multiple linear regression, artificial neural networks, support vector machine and random forest. The random forest model performed best and was used to predict SOC for several depth increments at a spatial resolution of 1 m (1×1 m). A high-resolution (1 m) land cover classification generated for this study is the most relevant predictive variable. The landscape mean SOC storage (0-150 cm) is estimated to be 8.3 ± 8.0 kg C m-2 and the SOC stored in the top meter (0-100 cm) to be 7.7 ± 6.2 kg C m-2. The predictive modeling highlights the relative importance of wetland areas and in particular peat plateaus for the landscape's SOC storage. The total SOC was also predicted at reduced spatial resolutions of 2, 10, 30, 100, 250 and 1000 m and shows a significant drop in land cover class detail and a tendency to underestimate the SOC at resolutions > 30 m. This is associated with the occurrence of many small-scale wetlands forming local hot-spots of SOC storage that are omitted at coarse resolutions. Sharp transitions in SOC storage associated with land cover and permafrost distribution are the most challenging methodological aspect. However, in this study, at local, regional and circum-Arctic scales, the main factor limiting robust SOC mapping efforts is the scarcity of soil pedon data from across the entire environmental space. For the Abisko region, past SOC and permafrost dynamics indicate that most of the SOC is barely 2000 years old and very dynamic. Future research needs to investigate the geomorphic response of permafrost degradation and the fate of SOC across all landscape compartments in post-permafrost landscapes.

  6. PET-CT in the sub-arctic region of Norway 2010–2013. At the edge of what is possible?

    International Nuclear Information System (INIS)

    Norum, Jan; Søndergaard, Ursula; Traasdahl, Erik; Nieder, Carsten; Tollåli, Geir; Andersen, Gry; Sundset, Rune

    2015-01-01

    It is challenging to obtain a similar access to positron emission tomography/computed tomography (PET-CT) within the whole region served. In the subarctic and arctic region of Norway, significant distances, weather conditions and seasonable darkness have been challenging when the health care provider has aimed for a high quality PET-CT service with similar availability to all inhabitants. The PET-CT service at the University Hospital of North Norway (UNN) was established in May 2010. The glucose analogue tracer fluorine-18 fluorodeoxyglucose (FDG) was delivered from Helsinki, Finland. An ambulatory PET-CT scanner was initially employed and a permanent local one was introduced in October 2011. In March 2014, we analysed retrospectively all data on the PET-CT exams performed at the Section of Nuclear Medicine, Department of Radiology during a 32 months time period 2010–13. The following patient data were recorded: gender, age, diagnosis, residence and distance of travelling. There were in total 796 exams in 706 patients. Four hundred sixty-one PET-CT exams per million inhabitants were, on average, performed per year. Lung cancer (32.7 %), malignant melanoma (11.3 %), colorectal cancer (10.9 %) and lymphoma (9.7 %) constituted two-thirds of all exams. Three-fourths were males and the median age was 63.5 years (range 15.2–91.4 years). The access to PET-CT exam varied within the region. The southern county (Nordland) experienced a significantly less access (p < 0.0001) to the regional service. Except for malignant melanoma, this finding was observed in all major cancer subgroups. In colorectal cancer and lymphoma a lower consumption of PET-CT was also observed in the northeastern county (Finnmark). Patients’ mean distance of travelling by car (one way) was 373 km (median 313 km, range 5–936 km). PET-CT was not similarly available within the region. Especially, inhabitants in the southern county experienced less access to the regional service. National and

  7. High-resolution digital mapping of soil organic carbon in permafrost terrain using machine learning: a case study in a sub-Arctic peatland environment

    Directory of Open Access Journals (Sweden)

    M. B. Siewert

    2018-03-01

    Full Text Available Soil organic carbon (SOC stored in northern peatlands and permafrost-affected soils are key components in the global carbon cycle. This article quantifies SOC stocks in a sub-Arctic mountainous peatland environment in the discontinuous permafrost zone in Abisko, northern Sweden. Four machine-learning techniques are evaluated for SOC quantification: multiple linear regression, artificial neural networks, support vector machine and random forest. The random forest model performed best and was used to predict SOC for several depth increments at a spatial resolution of 1 m (1×1 m. A high-resolution (1 m land cover classification generated for this study is the most relevant predictive variable. The landscape mean SOC storage (0–150 cm is estimated to be 8.3 ± 8.0 kg C m−2 and the SOC stored in the top meter (0–100 cm to be 7.7 ± 6.2 kg C m−2. The predictive modeling highlights the relative importance of wetland areas and in particular peat plateaus for the landscape's SOC storage. The total SOC was also predicted at reduced spatial resolutions of 2, 10, 30, 100, 250 and 1000 m and shows a significant drop in land cover class detail and a tendency to underestimate the SOC at resolutions  >  30 m. This is associated with the occurrence of many small-scale wetlands forming local hot-spots of SOC storage that are omitted at coarse resolutions. Sharp transitions in SOC storage associated with land cover and permafrost distribution are the most challenging methodological aspect. However, in this study, at local, regional and circum-Arctic scales, the main factor limiting robust SOC mapping efforts is the scarcity of soil pedon data from across the entire environmental space. For the Abisko region, past SOC and permafrost dynamics indicate that most of the SOC is barely 2000 years old and very dynamic. Future research needs to investigate the geomorphic response of permafrost degradation and the fate of

  8. Linking carbon and nitrogen cycling: Environmental transcription of mmoX, pmoA, and nifH by methane oxidizing Proteobacteria in a Sub-Arctic palsa peatland

    Science.gov (United States)

    Liebner, Susanne; Svenning, Mette M.

    2013-04-01

    Sub-Arctic terrestrial ecosystems are currently affected by climate change which causes degradation of stored organic carbon and emissions of greenhouse gases from microbial processes. Methane oxidizing bacteria (MOB) mitigate methane emissions and perform an important function in the soil-atmosphere interaction. In this study we investigated presence and environmental transcription of functional genes of MOB along the degradation of permafrost in a Sub-Arctic palsa peatland using molecular approaches. The acidic and oligotrophic peatland hosts a small number of active MOB among a seemingly specialized community. The methanotrophic community displayed a broad functional potential by transcribing genes for key enzymes involved in both carbon and nitrogen metabolisms including particulate and soluble methane monoogygenase (pMMO and sMMO) as well as nitrogenase. Transcription of mmoX that encodes for a subunit of the sMMO suggests an ecological importance of sMMO with a broad substrate range in this peatland. In situ transcripts of mmoX were tracked mainly to Methylocella related Beijerinckiaceae, and to relatives of Methylomonas while Methylocystis constituting the dominant group which utilizes pMMO. These results address interesting questions concerning in-situ substrate preferences of MOB, and the general importance of species that lack a pMMO for mitigating methane emissions. The importance of MOB for the nitrogen budget in this low pH, nitrogen limited habitat was identified by nifH transcripts of native methanotrophs. Hence, methane oxidizing Proteobacteria show an extended functional repertoire and importance for the biogeochemical cycling in this dynamic ecosystem of degrading permafrost.

  9. Reflectance spectra of subarctic lichens

    International Nuclear Information System (INIS)

    Petzold, D.E.; Goward, S.N.

    1988-01-01

    Lichens constitute a major portion of the ground cover of high latitude environments, but little has been reported concerning their in situ solar spectral reflectance properties. Knowledge of these properties is important for the interpretation of remotely sensed observations from high latitude regions, as well as in studies of high latitude ecology and energy balance climatology. The spectral reflectance of common boreal vascular plants is similar to that of vascular plants of the mid latitudes. The dominant lichens, in contrast, display variable reflectance patterns in visible wavelengths. The relative reflectance peak at 0.55 μm, common to green vegetation, is absent or indistinct in spectra of pervasive boreal forest and tundra lichens, despite the presence of chlorophyll in the inner algal cells. Lichens of the dominant genus, Cladina, display strong absorption of ultraviolet energy and short-wavelength blue light relative to their absorption in other visible wavelengths. Since the Cladinae dominate both the surface vegetation in open woodlands of the boreal forest and the low arctic tundra, their unusual spectral reflectance patterns will enable accurate monitoring of the boreal forest-tundra ecotone and detection of its vigor and movement in the future. (author)

  10. Heat Pumps in Subarctic Areas

    DEFF Research Database (Denmark)

    Atlason, Reynir Smari; Oddsson, Gudmundur Valur; Unnthorsson, Runar

    2017-01-01

    Geothermal heat pumps use the temperature difference between inside and outside areas to modify a refrigerant, either for heating or cooling. Doing so can lower the need for external heating energy for a household to some extent. The eventual impact depends on various factors, such as the external...... source for heating or cooling and the temperature difference. The use of geothermal heat pumps, and eventual benefits has not been studied in the context of frigid areas, such as in Iceland. In Iceland, only remote areas do not have access to district heating from geothermal energy where households may...... therefor benefit from using geothermal heat pumps. It is the intent of this study to explore the observed benefits of using geothermal heat pumps in Iceland, both financially and energetically. This study further elaborates on incentives provided by the Icelandic government. Real data was gathered from...

  11. Reflectance spectra of subarctic lichens

    Science.gov (United States)

    Petzold, Donald E.; Goward, Samuel N.

    1988-01-01

    Lichens constitute a major portion of the ground cover of high latitude environments, but little has been reported concerning their in situ solar spectral reflectance properties. Knowledge of these properties is important for the interpretation of remotely sensed observations from high latitude regions, as well as in studies of high latitude ecology and energy balance climatology. The spectral reflectance of common boreal vascular plants is similar to that of vascular plants of the midlatitudes. The dominant lichens, in contrast, display variable reflectance patterns in visible wavelengths. The relative reflectance peak at 0.55 microns, common to green vegetation, is absent or indistinct in spectra of pervasive boreal forest and tundra lichens, despite the presence of chlorophyll in the inner algal cells. Lichens of the dominant genus, Cladina, display strong absorption of ultraviolet energy and short-wavelength blue light relative to their absorption in other visible wavelengths. Since the Cladinae dominate both the surface vegetation in open woodlands of the boreal forest and the low arctic tundra, their unusual spectral reflectance patterns will enable accurate monitoring of the boreal forest-tundra ecotone and detection of its vigor and movement in the future.

  12. Spectrum and Frequency of the GJB2 Gene Pathogenic Variants in a Large Cohort of Patients with Hearing Impairment Living in a Subarctic Region of Russia (the Sakha Republic.

    Directory of Open Access Journals (Sweden)

    Nikolay A Barashkov

    Full Text Available Pathogenic variants in the GJB2 gene, encoding connexin 26, are known to be a major cause of hearing impairment (HI. More than 300 allelic variants have been identified in the GJB2 gene. Spectrum and allelic frequencies of the GJB2 gene vary significantly among different ethnic groups worldwide. Until now, the spectrum and frequency of the pathogenic variants in exon 1, exon 2 and the flanking intronic regions of the GJB2 gene have not been described thoroughly in the Sakha Republic (Yakutia, which is located in a subarctic region in Russia. The complete sequencing of the non-coding and coding regions of the GJB2 gene was performed in 393 patients with HI (Yakuts-296, Russians-51, mixed and other ethnicities-46 and in 187 normal hearing individuals of Yakut (n = 107 and Russian (n = 80 populations. In the total sample (n = 580, we revealed 12 allelic variants of the GJB2 gene, 8 of which were recessive pathogenic variants. Ten genotypes with biallelic recessive pathogenic variants in the GJB2 gene (in a homozygous or a compound heterozygous state were found in 192 out of 393 patients (48.85%. We found that the most frequent GJB2 pathogenic variant in the Yakut patients was c.-23+1G>A (51.82% and that the second most frequent was c.109G>A (2.37%, followed by c.35delG (1.64%. Pathogenic variants с.35delG (22.34%, c.-23+1G>A (5.31%, and c.313_326del14 (2.12% were found to be the most frequent among the Russian patients. The carrier frequencies of the c.-23+1G>A and с.109G>A pathogenic variants in the Yakut control group were 10.20% and 2.80%, respectively. The carrier frequencies of с.35delG and c.101T>C were identical (2.5% in the Russian control group. We found that the contribution of the GJB2 gene pathogenic variants in HI in the population of the Sakha Republic (48.85% was the highest among all of the previously studied regions of Asia. We suggest that extensive accumulation of the c.-23+1G>A pathogenic variant in the indigenous Yakut

  13. Spectrum and Frequency of the GJB2 Gene Pathogenic Variants in a Large Cohort of Patients with Hearing Impairment Living in a Subarctic Region of Russia (the Sakha Republic).

    Science.gov (United States)

    Barashkov, Nikolay A; Pshennikova, Vera G; Posukh, Olga L; Teryutin, Fedor M; Solovyev, Aisen V; Klarov, Leonid A; Romanov, Georgii P; Gotovtsev, Nyurgun N; Kozhevnikov, Andrey A; Kirillina, Elena V; Sidorova, Oksana G; Vasilyevа, Lena M; Fedotova, Elvira E; Morozov, Igor V; Bondar, Alexander A; Solovyevа, Natalya A; Kononova, Sardana K; Rafailov, Adyum M; Sazonov, Nikolay N; Alekseev, Anatoliy N; Tomsky, Mikhail I; Dzhemileva, Lilya U; Khusnutdinova, Elza K; Fedorova, Sardana A

    2016-01-01

    Pathogenic variants in the GJB2 gene, encoding connexin 26, are known to be a major cause of hearing impairment (HI). More than 300 allelic variants have been identified in the GJB2 gene. Spectrum and allelic frequencies of the GJB2 gene vary significantly among different ethnic groups worldwide. Until now, the spectrum and frequency of the pathogenic variants in exon 1, exon 2 and the flanking intronic regions of the GJB2 gene have not been described thoroughly in the Sakha Republic (Yakutia), which is located in a subarctic region in Russia. The complete sequencing of the non-coding and coding regions of the GJB2 gene was performed in 393 patients with HI (Yakuts-296, Russians-51, mixed and other ethnicities-46) and in 187 normal hearing individuals of Yakut (n = 107) and Russian (n = 80) populations. In the total sample (n = 580), we revealed 12 allelic variants of the GJB2 gene, 8 of which were recessive pathogenic variants. Ten genotypes with biallelic recessive pathogenic variants in the GJB2 gene (in a homozygous or a compound heterozygous state) were found in 192 out of 393 patients (48.85%). We found that the most frequent GJB2 pathogenic variant in the Yakut patients was c.-23+1G>A (51.82%) and that the second most frequent was c.109G>A (2.37%), followed by c.35delG (1.64%). Pathogenic variants с.35delG (22.34%), c.-23+1G>A (5.31%), and c.313_326del14 (2.12%) were found to be the most frequent among the Russian patients. The carrier frequencies of the c.-23+1G>A and с.109G>A pathogenic variants in the Yakut control group were 10.20% and 2.80%, respectively. The carrier frequencies of с.35delG and c.101T>C were identical (2.5%) in the Russian control group. We found that the contribution of the GJB2 gene pathogenic variants in HI in the population of the Sakha Republic (48.85%) was the highest among all of the previously studied regions of Asia. We suggest that extensive accumulation of the c.-23+1G>A pathogenic variant in the indigenous Yakut

  14. Aufeis accumulations in stream bottoms in arctic and subarctic environments as a possible indicator of geologic structure: Chapter F in Recent U.S. Geological Survey studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada--results of a 5-year project

    Science.gov (United States)

    Wanty, Richard B.; Wang, Bronwen; Vohden, Jim; Day, Warren C.; Gough, Larry P.; Gough, Larry P.; Day, Warren C.

    2007-01-01

    Thick accumulations of ice, called “aufeis,” form during winter along stream and river valleys in arctic and subarctic regions. In high-gradient alpine streams, aufeis forms mostly as a result of ground-water discharge into the stream channel. The ice occludes this discharge, perturbing the steady-state condition, and causing an incremental rise in the local water table until discharge occurs higher on the stream bank above the previously formed ice. Successive freezing of onlapping ice layers can lead to aufeis accumulations several meters thick.

  15. Tree species diversity in a seasonally-dry forest: the case of the Pinkaití site, in the Kayapó Indigenous Area, Southeastern limits of the Amazon Diversidade de espécies arbóreas em uma floresta sazonalmente seca: o caso da base de pesquisas do Pinkaití (PA, na Terra Indígena Kayapó, limite sudoeste da Amazônia

    Directory of Open Access Journals (Sweden)

    Rodolfo Salm

    2004-09-01

    Full Text Available This study investigates patterns of forest structure and tree species diversity in an anthropogenic palm grove and undisturbed areas at the seasonally-dry Pinkaití research station, in the Kayapó Indigenous Area. This site, managed by the Conservation International do Brasil, is the most southeastern site floristically surveyed in the Amazon until now. The secondary and a nearby undisturbed forest were sampled in a group of 52 floristic plots of 0.0625-ha (25x25-m where all trees with DBH > 10 cm were measured and identified. The analyses were complemented with other two floristic plots of 1-ha (10x1000-m. The present study has shown that the Pinkaití, like other seasonally-dry forests, have great heterogeneity in forest structure and composition, associated with biotic characteristics of the most important tree species, natural disturbance and history of land-use. The palm grove, moderately dominated by the arborescent palm Attalea maripa (Aubl. Mart., presented high tree species diversity and was floristically similar to undisturbed forests at the study site. It is discussed the importance of large arborescent palms for the seasonally-dry Amazon forests regeneration.Este estudo compara a florística e estrutura e a diversidade de espécies arbóreas de um palmeiral antropogênico e áreas não perturbadas na floresta sazonalmente seca da base de pesquisas ecológicas do Pinkaití, na Terra Indígena Kayapó. Esta base de estudos, administrada pela Conservation International do Brasil, é a área mais ao sudoeste até o momento floristicamente amostrada na Amazônia. Uma mancha de floresta secundária e uma floresta não perturbada adjacente foram amostradas com um grupo de 52 parcelas de 0,0625-ha (25x25-m onde todas as árvores com DAP > 10 cm foram medidas e identificadas. As análises foram complementadas com outras duas parcelas de 1-ha (10x1000-m. Este estudo mostrou que o Pinkaití, como outras florestas sazonalmente secas, tem grande

  16. African Heath Sciences Vol 7 No 3.p65

    African Journals Online (AJOL)

    FOMCS2

    Conclusion: The burden of HIV infection in the medical emergency unit is high and majority of the patients who ... Key words:HIV/AIDS, Eligibility for antiretroviral therapy, Hospitals, Africa. African ... National Council of Science and Technology.

  17. [Heath and political regimes: presidential or parliamentary government for Colombia?].

    Science.gov (United States)

    Idrovo, Alvaro J

    2007-01-01

    Changing the presidential regime for a parliamentarian one is currently be-ing discussed in Colombia. This preliminary study explores the potential effects on health of both presidential and parliamentary regimes by using world-wide data. An ecological study was undertaken using countries from which comparable information concerning life-expectancy at birth, political regime, economic development, inequality in income, social capital (as measured by general-ised trust or Corruption Perceptions Index), political rights, civil freedom and cultural diversity could be obtained. Life-expectancy at birth and macro-determinants were compared between both political regimes. The co-relationship between these macro-determinants was estimated and the relationship between political regimen and life-expectancy at birth was estimated using robust regression. Crude analysis revealed that parliamentary countries have greater life-expectancy at birth than countries having a presidential regime. Significant co-relationships between all macro-determinants were observed. No differential effects were observed between both political regimes regarding life-expectancy at birth in multiple robust regressions. There is no evidence that presidential or parliamentary regimes provide greater levels of health for the population. It is suggested that public health policies be focused on other macro-determinants having more known effects on health, such as income inequality.

  18. African Heath Sciences Vol 7 No 4.p65

    African Journals Online (AJOL)

    FOMCS2

    Background: This study investigated the emotional and behavioral problems of ... problems, we recommend setting up a National Policy and Support Services .... In each school a registry of all the students in ... Cooper's Self Report Measure of Social Adjustment scale ... standardized symptom checklists for the International.

  19. Environment of oocyte and embryo determines heath of IVP offspring

    NARCIS (Netherlands)

    Kruip, T.A.M.; Bevers, M.M.; Kemp, B.

    2000-01-01

    In vitro embryo production (IVP) enhances the number of offspring from a single female and offers the possibility of accelerated genetic progress in animal husbandry. However, it also leads to a low but unacceptable percentage of anomalies in the offspring. The aim of this paper is to introduce the

  20. Big Data and Heath Impacts of Drinking Water Quality Violation

    Science.gov (United States)

    Allaire, M.; Zheng, S.; Lall, U.

    2017-12-01

    Health impacts of drinking water quality violations are only understood at a coarse level in the United States. This limits identification of threats to water security in communities across the country. Substantial under-reporting is suspected due to requirements at U.S. public health institutes that water borne illnesses be confirmed by health providers. In the era of `big data', emerging information sources could offer insight into waterborne disease trends. In this study, we explore the use of fine-resolution sales data for over-the-counter medicine to estimate the health impacts of drinking water quality violations. We also demonstrate how unreported water quality issues can be detected by observing market behavior. We match a panel of supermarket sales data for the U.S. at the weekly level with geocoded violations data from 2006-2015. We estimate the change in anti-diarrheal medicine sale due to drinking water violations using a fixed effects model. We find that water quality violations have considerable effects on medicine sales. Sales nearly double due to Tier 1 violations, which pose an immediate health risk, and sales increase 15.1 percent due to violations related to microorganisms. Furthermore, our estimate of diarrheal illness cases associated with water quality violations indicates that the Centers for Disease Control and Prevention (CDC) reporting system may only capture about one percent of diarrheal cases due to impaired water. Incorporating medicine sales data could offer national public health institutes a game-changing way to improve monitoring of disease outbreaks. Since many disease cases are not formally diagnosed by health providers, consumption information could provide additional information to remedy under-reporting issues and improve water security in communities across the United States.

  1. African Heath Sciences Vol 7 No 2.p65

    African Journals Online (AJOL)

    FOMCS2

    2007-06-02

    Jun 2, 2007 ... Case Western Reserve University, Cleveland, Ohio. Abstract ... bed tertiary care, referral hospital located in Kampala, ... tion among patients admitted to the medical emergency ..... and the Fogarty International Center- Ellison.

  2. African Heath Sciences Vol 7 No 2.p65

    African Journals Online (AJOL)

    FOMCS2

    2007-06-02

    Jun 2, 2007 ... by 30 cycles of denaturation at 94oC for 30 sec, annealing at 60oC for 1 min ... PCR product and 2µL of loading buffer) was analyzed by electrophoresis .... tions and then self-medicate with over-the-counter antifungals, when ...

  3. C:\\My Documents\\African Heath S

    African Journals Online (AJOL)

    administratory

    Meat inspection for human consumption is a legal requirement in many a part of the world, but the reliability for this routine procedure to detect ... Ikoona E, Kalyesubula I, Kawuma M. Ocular manifestations in paediatric HIV/AIDS patients in Mulago Hospital,. Uganda. African Health Sciences 2003: 3(2) 83 – 86. 6. Anyama N ...

  4. C:\\My Documents\\African Heath S

    African Journals Online (AJOL)

    long children have been marginalized. For so long ... neglect, abuse or malnutrition at a critical period of development can ... measurable But survival falls so far short of the deeper and more ..... has not set in or memory lost. But what about ...

  5. African Heath Sciences Vol 7 No 4.p65

    African Journals Online (AJOL)

    FOMCS2

    counseling interventions aimed at dispelling misconceptions about HIV/AIDS should be ... homosexuality and intravenous drug addiction. ... HIV/AIDS prevention and control strategies ... would keep the infection of a family member a secret.

  6. African Heath Sciences Vol 7 No 4.p65

    African Journals Online (AJOL)

    FOMCS2

    urinary tract bacterial infections detected in urine samples at a hospital in ... be the result of anatomic abnormalities, but there is no plausible explanation in others2. ... preparation of fresh-centrifuged urine was made from each urine specimen ...

  7. Heath effects and medical application of non-ionizing radiation

    International Nuclear Information System (INIS)

    Nusslin, F.; Van Deventer, E.; Shannoun, F.

    2010-01-01

    Long-term effects (Cancer) Childhood leukemia ELF magnetic fields classified as Group 2B Possibly Carcinogenic based on limited human data (epidemiologic studies) of childhood leukemia and inadequate animal data Other exposures and outcomes considered inadequate to classify IARC Monograph (vol. 80, 2002) WHO EHC Monograph (vol. 238, 2007) Breast cancer The evidence has been weakened considerably and does not support an association Adult brain cancer and leukaemia. Short-term effects Established biological effects from acute exposure at high levels (well above 100 µT) that are explained by recognized biophysical mechanisms Consistent epidemiological evidence suggests that an increased risk for childhood leukaemia is associated with chronic low intensity ELF magnetic field exposure However, the evidence for a causal association is weak and the impact on public health uncertain.Thermal effects Radiofrequency waves can cause tissue heating, so-called thermal effects Heating >1oC activates physiological processes, which can influence activity of the nervous system, influence fertility, fetal development, cause cataracts All established health effects of RF exposure are clearly related to heating Non-thermal effects (?)While RF energy can interact with body tissues at levels too low to cause any significant heating, no study has shown adverse health effects at exposure levels below international guideline limits

  8. African Heath Sciences Vol 8 No 1.p65

    African Journals Online (AJOL)

    Harriet

    Abstract. Background: Mature sacrococcygeal teratomas (SCT) are uncommon neoplasms comprised of mixed elements derived from the three germ cell layers. They attract attention because of their gross appearance and bizarre histology. Aim: To demonstrate the clinical presentation and management of mature SCT in a ...

  9. Pregnancy and child heath outcomes among adolescents in Ethiopia

    African Journals Online (AJOL)

    A total of 663 teenage and 721 adult mothers who gave birth to their first child within five years preceding the survey were identified from the dataset. Results: Significantly larger proportion of the teenage mothers, were from rural areas, were poorer, less educated, and gave a history of no marriage. Controlling for potential ...

  10. 2016-2017 Travel Expense Reports for Alanna Heath, Governor

    International Development Research Centre (IDRC) Digital Library (Canada)

    Beata Bialic

    14 to 2016-08-19. Destination(s):. Colombia. Airfare: $2,632.41. Other. Transportation: $39.85. Accommodation: $608.12. Meals and. Incidentals: $346.50. Other: $75.50. Total: $3,702.38. Comments: 2016-2017 Travel Expense Reports for ...

  11. African Heath Sciences Vol 8 No 1.p65

    African Journals Online (AJOL)

    Harriet

    2002-11-30

    Nov 30, 2002 ... Conclusion: Severe bleeding in placenta praevia is associated with high maternal morbidity and ... This is because as pregnancy advances the lower uterine ... Abnormal placentation and smoking have been attributed.

  12. African Heath Sciences Vol 7 No 4.p65

    African Journals Online (AJOL)

    FOMCS2

    no evidence of significant associative interactions between Hib-CRM197 and MenC-CRM197 in saline-based buffers, pH 7.2. African ... aggregation of vaccine saccharide or protein components. 17, 18 ... chromatography and for analysis of the generated data. .... protein would be expected to elute after the main MenC-.

  13. African Heath Sciences Vol 7 No 4.p65

    African Journals Online (AJOL)

    FOMCS2

    Department of Biochemistry and Microbiology, Faculty of Science, University of Buea, ... Data were analysed using the Fisher exact test and statistical significance .... pension. Briefly, it was prepared as follows: 4-5 colo- nies of the isolates ...

  14. African Heath Sciences Vol 7 No 3.p65

    African Journals Online (AJOL)

    FOMCS2

    nifestations such as recurrent abortions, arterial and venous thrombosis, and thrombocytopenia3. Cutaneous symptoms of this syndrome include leg ulcers and livedo reticularis4. Neurological disorders such as dementia, epilepsy, chorea and migraine5 can also occur. The first antiphospholipid antibody was detected in ...

  15. [The dynamics of heath indicators of population of industrial town].

    Science.gov (United States)

    Kalinkin, D E; Karpov, A B; Takhauov, R M; Samoĭlova, Iu A

    2013-01-01

    The article presents the results of an